Restocking Programs Research Articles

Value Chain Opportunities for Pacific Coastal Resources

Oceanic tuna fisheries are a major contributor to the economic health of Pacific Island countries (PICs), with coastal fisheries underpinning the livelihoods of locals, providing food security, significant employment, culture, and human welfare. Livelihood development across various PICs is hindered by the inability to harness the maximum potential of coastal fishery resources, particularly through the lack of identifying targeted development needs. Development of coastal value chains facilitates resilience by reducing local reliance on tuna fisheries and associated vulnerability to tuna industry dynamics to support socio-economic development throughout the PICs while maintaining food security. The aim of this paper is to identify priority opportunities for developing coastal resource value chains in PICs, targeting increased local economic resilience and food security. A methodology developed by the World Bank was used to assist stakeholders and policymakers to coalesce around common strategies for the value chains. Six value chains were identified: beche-de-mer; ornamental black pearls and Trochus shell; fresh fish for the domestic market; reef fish exports; export of live lobsters; and export of aquarium fish products. Porter’s Five Forces framework was used for value chain analysis, and strategic repositioning considerations and areas for investment support within high-priority value chains were identified. Fisheries data collection, community-based sustainable management and aquaculture restocking programmes, habitat restoration, development of the cold chain, air freight logistics for export, and facilitating international market connections and market access were identified for external investment support.

Survival and space use of a restocked Iberian rabbit population in a semi-natural enclosure

Restocking is widely used to recover depleted wild rabbit, Oryctolagus cuniculus, populations in the Iberian Peninsula. However, in general, it’s costly and unsuccessful. In this work, we developed a wild rabbit restocking protocol based on recommendations from existing literature to enhance its success. We released 75 Iberian rabbits, Oryctolagus cuniculus algirus, in a 1.7-ha restocking park, a fenced semi-natural enclosure, with similar resources as the surrounding area, in Monchique, southern Portugal. We tracked 22 radio-collared rabbits (sex ratio 1:1) for 6 months. We released some rabbits inside warrens, and others in shrub patches. After a 72-day acclimation period, we opened the restocking park passages to allow the rabbits to disperse. We then accessed rabbit survival and space use. We found that survival rates stabilised 74 days after restocking, with an estimated probability of survival at the end of the study of 35.4%. Predation by birds of prey was the primary cause of death. Regarding space use, the restocked population took 96.364 ± SE 12.615 days to stabilise home ranges. After the acclimation period, the maximum distances travelled by rabbits significantly increased. However, before and after the opening of the passages, the home ranges remained within the limits of the restocking park, indicating that the surviving rabbits settled within the enclosure. Rabbits released within warrens had significantly smaller core areas, while those released in shrubs exhibited more ranging behaviour. Considering our findings, we recommend implementing several measures to improve similar rabbit restocking programs.

A Weight-of-Evidence Approach for Understanding the Recovery of Okanagan Sockeye Salmon

The productivity of Pacific Sockeye salmon (Oncorhynchus nerka) in the Columbia River has been declining over the past century. Yet, the Okanagan River Sockeye salmon population, which spawns in the Okanagan River, a Canadian tributary of the Columbia River, has seen a remarkable turnaround in abundance. Different hypotheses and lines of evidence covering multiple spatial scales have been proposed to explain this recovery; but they have never been comprehensively assessed. We adopted a weight-of-evidence approach to systematically assess the relative likelihood that each of these causal hypotheses contributed to the observed recovery. Our analysis disentangles the relative consequences of a set of environmental management actions that have been implemented to augment the Sockeye salmon freshwater productivity, while accounting for changes in freshwater and marine environmental conditions. Our list of potentially explanatory causal factors (anthropogenic and natural) included: (1) changes in escapement concurrent with improving local fish passage, (2) the implementation of fish-friendly flows in the Okanagan River, (3) initiating a hatchery restocking program, (4) potential improvements to Columbia dam operations to support higher relative survival of out-migrating juvenile fish, (5) possible shifts in survival-favorable conditions in the coastal marine environment for ocean-going life stages, and (6) broader changes to multi-stock harvest regimes in the Columbia River. Our assessment leveraged comparisons with the population dynamics of another Sockeye salmon stock in the Columbia River basin to differentiate between the impacts of management actions taken within the Okanagan watershed (our focus) from those occurring over the broader basin and marine scale. The results suggest that while shifts towards survival-favorable conditions in the coastal marine environment in 2007 played an important role in the upturn of the Okanagan population, alone it cannot explain the rate at which the Okanagan River Sockeye salmon recovered. Strong evidence supports the combined effect of increased escapement in conjunction with establishing and securing fish-friendly flows during spawning, incubation, and alevin emergence. Additionally, Sockeye salmon restocking improved the resilience of the stock against density-independent mortality events. These combined basin-level management actions played a pivotal role in magnifying the recovery trajectory afforded by improved marine survivorship. The spectacular response of the Okanagan River Sockeye salmon to the holistic perspectives and management interventions of Indigenous and other caretakers provides hope that other Pacific salmon stocks can be stabilized and recovered.

Genetic Diversity and Distribution of Haplotypes of Freshwater Eel in Baltic Lakeland Based on Mitochondrial DNA D-Loop and Cytochrome b Sequence Variation

The European eel (Anguilla anguilla (L.)) is a unique catadromous euryhaline fish and the only anguillid eel species classified as ‘critically endangered’. The Baltic Lakeland area contains naturally recruited and introduced eels. There is great uncertainty regarding a baseline for the location and number of naturally dispersed eels in the region. Little is known about the genetic structure of the European eel populations in Baltic countries. The estimation of population genetic structure is important for the efficient management of naturally recruited and introduced eels. Two mitochondrial regions were used to investigate the genetic structure within and between eel samples from 11 waterbodies. In this study, new, unique, and widely distributed haplotypes were revealed. The studied eel population in the Baltic Lakeland shows high genetic diversity, which is possibly a result of intensive restocking programs. Sequences characterized for Anguilla rostrata were revealed in both mitochondrial regions. Understanding the genetic structure of eel populations worldwide is crucial for conservation efforts. Eel restocking in waterbodies where natural migration is restricted contributes to diversity loss for the world gene pool of eels.

Genetic Characterization of Endangered Sterlet (Acipenser ruthenus, Linnaeus 1758) Gene Bank Broodstock, Natural and Cultured Populations in Hungary

The sterlet (Acipenser ruthenus) is the smallest-bodied endangered species among the six native sturgeon species of the Danube River, and self-sustaining populations still inhabit the Hungarian section of the Danube River and its largest tributary, the Tisza River. Their populations are drastically decreasing; however, they still have natural reproduction in these habitats. For the genetic conservation of the species, an ex situ gene bank is maintained in Hungary. The present study aimed to analyze the genetic resources of a gene bank with a near 40-year history and to compare it with natural populations and farmed stocks. Twelve microsatellites were used for population genetics analyses and individual genotyping of 268 specimens from two natural habitats (Danube and Tisza Rivers) and three captive stocks (a gene bank broodstock and two farms). Microsatellites revealed similar patterns among wild populations and gene bank stocks and did not show genetic differentiation (FST: 0.016–0.017) among them. These results confirmed that the gene bank broodstock properly represents the genetic background of the Danube and Tisza populations and is suitable as a source of breeding materials for the restocking programs. Negative trends were detected in the farmed stocks, reflected in reduced polymorphism at a few loci. The results of the principal component analyses indicate the farm stocks’ separation from the wild and gene bank stocks. The present genetic characterization study reveals a valuable captive stock of the endangered sterlet populations and provides unique information about the genetic similarities and differences among farms and wild stocks in Hungary. Our results provide information that contributes to preserving the genetic structure and variability in sterlet populations and supports the management of gene bank broodstock—avoiding inbreeding and preserving the unique genetic background of the Carpathian basin.

Stakeholders' perception and willingness-to-pay for an aquaculture-based fisheries enhancement program for coastal cod in Southern Norway

The coastal cod fishery in Southern Norway has experienced a significant decline over the last decades. Recreational fishing for cod in the eastern part of the country is currently banned. Fisheries managers have adopted a variety of strategies to sustain the populations for resource users. Aquaculture-based fisheries enhancement has been considered as an alternative intervention to rebuild overexploited cod stock or to improve the opportunity for marine fishing. However, there has been a debate regarding its ecological and social effectiveness among stakeholders. In this paper, we conducted an online contingent valuation survey aiming to understand stakeholders' perceptions and attitude towards restocking of hatchery-produced juveniles as a potential restoration approach to rebuild depleted coastal cod populations and their willingness to pay for the implementation of such an enhancement program in southern Norway. Results indicate that the public has a positive perception to the potential restocking program. The average Willingness-To-Pay (WTP), e.g. fishing license fee, is approximately 175 NOK and 693 NOK if all of the respondents, and only counting those who are willing to, contribute. The introduction of a minimum fishing license fee of 175 NOK (approximately 17€) would cover the cost of production of over 20 million juvenile cod of appropriate size for release. Age of the respondents, the frequency of their fishing trips, and their perception of the decline of coastal cod were the main drivers for the WTP contribution while the amount of the WTP was strongly correlated to targeting particular species, educational level, and place of residence. Considering the critical situation of the coastal cod populations in southern Norway, together with the significant advances in cod rearing techniques, in fish tagging technology and the maturation of fisheries enhancement as science, and the positive stakeholders' perceptions and attitudes towards such an aquaculture-based enhancement program revealed from this study, it may be the time to re-evaluate the potential integration of a holistic cod restocking program within Norwegian coastal zone management.

Demographic and conservation genomic assessment of the threatened marbled teal (Marmaronetta angustirostris).

Genetic assessment of species that have experienced dramatic population declines provides critical information that is instrumental for the design of conservation recovery programs. Here, we use different sources of molecular data (mtDNA and ddRAD-seq) to evaluate the genetic status of wild and captive populations of marbled teal (Marmaronetta angustirostris), a duck species classified as critically endangered in Spain and near threatened at a global scale. First, we determined the evolutionary and demographic trajectories of the wild population from Spain and the currently much larger population from Iraq, which is also the documented source of European zoo stocks. Second, we evaluated the suitability of the different captive populations for ongoing restocking programs in Spain and assessed their potential impact on the genetic composition of wild populations. Populations from Spain and Iraq were assigned to distinct genetic clusters, albeit with an overall low level of genetic differentiation, in line with their recent divergence (<8000 years ago) and lack of phylogeographic structure in the species. Demogenomic inferences revealed that the two populations have experienced parallel demographic trajectories, with a marked bottleneck during the last glacial period followed by a sudden demographic expansion and stability since the onset of the Holocene. The wild population from Spain presented high levels of inbreeding, but we found no evidence of recent genetic bottlenecks compatible with the human-driven decline of the species during the past century. The captive populations from the two Spanish centers involved in restocking programs showed genetic introgression from European zoos; however, we found limited evidence of introgression from the zoo genetic stock into the wild population from Spain, suggesting captive-bred birds have limited breeding success in the wild. Our study illustrates how ex situ conservation programs should consider the genetic distinctiveness of populations when establishing breeding stocks and highlights the importance of genetically assessing captive populations prior to reinforcement actions.

Increasing Population Status of Broad-Snouted Caiman (Caiman latirostris) Based on Sustainable Use Strategies in a Managed Protected Area in Santa Fe, Argentina.

People and crocodilians have engaged in interactions since the earliest human settlements. After many years of escalating non-regulated use, coupled with emerging threats such as habitat modification, environmental pollution, and the exponential growth of human populations, natural crocodilian populations have been pushed to the brink of extinction. To prevent this, various initiatives have implemented strategies to prevent local extinction. Reinforcing wild populations through reintroductions and head-starting programs has been considered the safest approach to recovering crocodilian populations. Subsequently, the concept of sustainability emerged. In the case of many historically exploited crocodilian species, it became evident that rational utilization need not adversely affect population status; on the contrary, there were clear signs of recovery when local communities were involved. In 1990, the broad-snouted caiman (Caiman latirostris) was in a critical state due to decades of poaching and the aforementioned threats. In response, the "Monitoring and restocking program of the broad-snouted caiman for management purposes", commonly known as Proyecto Yacaré, was established to study population abundance and assess the biological, ecological, and social response to this management methodology. As a result of the eggs's harvest, a proportion equivalent to or greater than what would have survived in natural conditions was released into the original habitat where the eggs were collected. The surplus was allocated for leather and meat production with a focus on economic and environmentally sustainable practices, without affecting biodiversity or threats to the managed species. The in situ work carried out by this program has been crucial for the recovery of broad-snouted caiman populations under the "incentives for conservation" system, whereby local communities receive benefits for nest identification and egg harvesting. Over time, conservation incentives have become significant contributors to regional economies. This study illustrates how C. latirostris populations increased due to the implementation of egg harvesting by local communities in a natural reserve for management purposes. This population increase was detected through continuous night monitoring and an analysis of the number of nests in the area. Currently, C. latirostris populations have transitioned from being among the most threatened to becoming one of the most abundant throughout their distribution area. Based on the analyzed information, we may affirm that the commercial value of these species is one of the most relevant aspects contributing to the sustainability of these programs, primarily due to the change in perception generated among local communities. Therefore, identifying and controlling factors affecting these programs are fundamental for the conservation of these species.

Reproductive performance of the fluted clams (Tridacna squamosa) through different serotonin hormone doses for spawning induction

Exploring the reproductive performance one of the giant clam species being cultured in Indonesia. The fluted clams (Tridacna squamosa) are a keystone species for Indonesia’s marineculture and restocking program, categorized as a protected commodities by Convention on International Trade in Endangered Species (CITES) due to anthropogenic pressure on wild population. To assess and improve their reproductive performance, induction of different serotonin was applied consisting of control (0 mM), T1 (1.1 mM), T2 (1.4 mM), and T3 (1.7 mM). New significant insights emerge, results indicate response’s time of pre-spawning T1 and T2 were approximately 45 s, while T3 was 60 s, respectively T2 is highest spawning success at 91.67%, contrasting with 50% by T3, also spawning latency varied, with the quickest gamete release (3 min) by T2, on the contrary T3 (4 min). Observed eggs released at approximately 24 min (T2), 84 min (T1) with an egg diameter of 128.72±1.56 μm yet absent in T3. Polynomial regression of fecundity from differential dosing approach attained an R² = 0.3885, highlights an optimal 1.36 mM dosage for maximizing spawning performance, indicating T2 as an adequate dose with moderate egg abnormalities 8.7% and. FR, HR, and SR ranged from to 70-80% respectively.

Change in Reef Fish Assemblages along Depth Gradient at Gili Rakit and Gili Lipan Marine Protected Areas (MPAs)

Since 2010, Marine Protected Areas (MPAs) have been established in Indonesia to ensure the sustainable management of coral reef ecosystems. This study examines fish assemblages across varying depths and MPAs management areas, specifically assessing the suitability of Gili Rakit and Gili Lipan MPAs. The study concludes that deeper coral reefs have higher reef fish abundance, with a majority of carnivores, planktivores, and omnivores. Gili Taekebo has the lowest abundance and species richness, while Pulau Lipan has the highest. The target reef fish are primarily found in the core zone, rehabilitation, and open access management types. Based on the findings, MPAs should prioritize sites with gradient depth coral reefs and complex habitats to enhance reef fish biodiversity richness. Takad Tabampang and Pulau Bedil are recommended as sustainable fisheries management types, while Gili Taekebo could benefit from rehabilitation or open access management. Pulau Lipan and Labajo may benefit from target fish re-stocking programs.

GENETIC DIVERSITY AND POPULATION STRUCTURE OF THE EUROPEAN EEL (ANGUILLA ANGUILLA) IN BALTIC LAKELAND

Anguilla anguilla (Linnaeus, 1758) is the unique catadromous fish species in the Latvian fauna. The Baltic Lakeland area representing naturally recruited and introduced eels. In recent decades, its population has decreased not only in Latvia, but also in Europe. European eel critically endangered due to overfishing of glass eels, blocking of migratory paths, deaths in HPS turbines, water pollution and diseases and parasites. Only some bodies of water are freely accessible to natural migration of eels in Latvia.Currently, its position has been recognized as being critical, and a range of normative acts have been adopted for its restoration, such as the Regulation EC 1100/2007. The restocking programs of the European eel Anguilla anguilla have been conducted for nearly one century in Latvia.This study provides the first data on population structure of freshwater eels in Baltic Lakeland, for use in eel conservation and management of aquaculture on a regional and/or global scale. By analysing the sequences of the Cyt b gene of mtDNA for individuals caught in locations throughout in Baltic Lakeland, we determined the population genetic structure of A. anguilla in the area. The diversity of haplotypes was studied in ten waterbodies from part of Baltic Lakeland, namely Lake Sīvers, Lake Usmas, Lake Ķišezers, Lake Liepājas, Lake Alūksnes, Lake Rāznas, Lake Vialikija Švakšty, Lake Svir, Lake Myadzyel, Myadzelka river. Additionally, this study investigated the affinity of the Latvian populations to other A. anguilla populations around the world.This is the first report about eel’s population genetic diversity in Baltic Lakeland. Haplotype variation was different in all investigated waterbodies. In current studies seven new unique haplotypes were detected. Eel population in Baltic Lakeland shows quite high genetic diversity and rapid population expansions, which possibly is results of intensive restocking program. Sequences characterized Anguilla rostrata in Lake Alūksnes were detected.

A qPCR-based method to detect the eel parasitic nematode Anguillicola crassus in intermediate and final hosts.

Being able to systematically detect parasitic infection, even when no visual signs of infection are present, is crucial to the establishment of accurate conservation policies. The nematode Anguillicola crassus infects the swimbladder of anguillid species and is a potential threat for eel populations. In North America, naïve hosts such as the American eel Anguilla rostrata are affected by this infection. The accidental introduction of A. crassus following restocking programs may contribute to the actual decline of the American eel in Canada. We present a quantitative real time PCR-based method to detect A. crassus infection in final and intermediate hosts. We tested two protocols on samples from different geographical origins in Canada: 1) a general detection of A. crassus DNA in pools of young final hosts (glass eels) or crustacean intermediate hosts 2) a detection at the individual scale by analyzing swim bladders from elvers, or from adult yellow and silver eels. The DNA of A. crassus was detected in one pool of zooplankton (intermediate host) from the Richelieu River (Montérégie-Québec), as well as in individual swim bladders of 13 elvers from Grande and Petite Trinité rivers (Côte-Nord-Québec). We suggest that our qPCR approach could be used in a quantitative way to estimate the parasitic burden in individual swim bladders of elvers. Our method, which goes beyond most of previous developed protocols that restricted the diagnosis of A. crassus to the moment when it was fully established in its final host, should help to detect early A. crassus infection in nature.

Genome-wide SNP analyses reveal a substantial gene flow and isolated-genetic structure of sea cucumber Holothuria leucospilota populations in Western Central Pacific

The black sea cucumber Holothuria leucospilota is a commercially exploited species in the Western and Central Pacific region including Australia and Vietnam, where it has been overfished. There is interest to develop captive breeding, sea ranching and restocking programs for H. leucospilota. However, the wide distribution of this species could lead to genetic structure among site, which needs to be considered for responsible genetic management for example, restocking. This is the first study to investigate population genetics in H. leucospilota, between Australia and Vietnam, using single nucleotide polymorphisms (SNPs). The results indicated that there was high gene flow (Nm > 4) and genetic similarities among three Vietnamese populations, which inferred a high panmictic stock structure in Vietnam. Less gene flow (Nm > 1) was indicated between Vietnam and Mooloolaba (Eastern Australia) populations, and there was a significant genetic differentiation among any Vietnamese populations and Mooloolaba population (FST from 0.034 to 0.043; P < 0.05). Surprisingly, there was a major genetic difference (FST > 0.2) and a restricted gene flow (Nm <1) between Darwin (Northern Australia) population and other sea cucumber populations studied (Vietnam and Eastern Australia), which revealed a genetic break/divergence in Darwin. Based on these findings, we can propose that the Vietnamese sea cucumber stocks be considered as a single genetic stock with concordant implications for genetic management. We consider whether the genetic differences in the Darwin stock arise from bottlenecking and are not reflective of adaptive differences. In summary, the results from this study provide basic genetic information on H. leucospilota populations, that would help to design restocking management plans, genetic conservation initiatives and sea ranching programs for H. leucospilota.

The environmental licensing of hydroelectrics and the interface with migratory fish and aquaculture in Brazil

In this review, we present a background on the Brazilian Federal Legislation on the environmental licensing of hydroelectric plants focusing on the procedure of the repair of environmental damage caused by dams to migratory fish. To that end, the Brazilian electrical matrix was first addressed, thus highlighting the significant contribution of the energy produced by hydroelectric projects. To better contextualize the characteristics of the legislation, separate sections concerning illustrative reports of the effects of dams on migratory fish and the current panorama of aquaculture in Brazil and in the world were included. In this review, we also present a discussion on the specific legislation concerning a mitigation measure, the “fish restocking programs,” which have the potential to promote fishing and aquaculture, but still lack a scientific basis on their effectiveness and correct application. An assessment of this historical process in Brazil indicates that different mitigation measures imposed to obtain operating licenses by hydroelectric plants vary among different hydroelectric projects and that this heterogeneity in the conditions imposed may have effects (of unknown proportions) on local fish communities. Considering the absence of a specific device foreseen in the law that requires the owner or concessionaire of dams in watercourses to provide for fish restocking programs or specific ichthyofauna conservation programs, the issue seems to depend on the discretion of the licensing agency to demand that the hydroelectric plant operators carry out the reintroduction of fish in their reservoirs. This review concludes that there are political and scientific issues to be debated and explored in order to improve public policies on this topic of extreme relevance for society.

Abortions in Peste Des Petits Ruminants (PPR) infected flocks in Yola North of Adamawa and Askira Uba areas of Borno State, Nigeria

Peste des petits ruminants (PPR) is a highly contagious viral disease of sheep and goats with as high as 90% morbidity and 80% mortality rates. Although, its substantial economic consequences are reported in goats worldwide, there are currently little information regarding abortion cases in PPR endemic areas in Nigeria. This study investigated occurrences of abortion among PPR infected goats in Yola North and Askira Uba local government areas of Adamawa and Borno States respectively. The study involved analysis of clinical case records of two thousand Sahel goats (n = 2000) procured as part of a livestock restocking program by a government agency. The goats were purchased from local markets and held in quarantine for 2 weeks during which PPR infection was monitored. In the study, a fast spreading infection characterized by severe dehydration, respiratory difficulty, pyrexia, depression, anorexia, nasal and ocular discharges and death of many infected goats informed a suspicion of PPR infection. The number of abortions, mortality and age of the animals were recorded during the investigation. Data were organized in a 2×2 contingency table and analyzed using Chi-square. The overall mortality in both populations was 42% and the occurrence of abortion was 1% and 3% in Yola North and Askira Uba holding sites respectively. The proportion of abortions did not differ significantly (p &gt; 0.05) between both populations but there was a positive association indicated as r = 0.4264 and 0.4638 between the occurrence of abortion and mortality in Yola North and Askira Uba holding sites respectively. In addition, the severity in clinical manifestation of the disease appeared higher in younger goats (&lt; 1 years) than the adult ones. These findings suggest that PPR infection could be associated with abortions in goat flocks found in these PPR endemic areas.

Evaluating performance of data-limited management procedures in an ecosystem perspective: A case study for Larimichthys crocea (Sciaenidae) in the Min River Estuary, China

Management Strategy Evaluation (MSE) evaluates the performance of alternative management strategies. However, the potential ecosystem effects of the management procedures (MPs) are less evaluated. As one of the four top commercial marine fisheries of China, the fishery of the large yellow croaker Larimichthys crocea (LYC) collapsed in the late 1980s due to the exceeded fishing pressure on spawning and over-wintering aggregations. Long-term and large scale restocking programs for the recovery of LYC fishery have been conducted widely along the eastern coast of China, but its ecosystem impacts and ecological carrying capacity (ECC) were not well understood and assessed. The species-specific assessment and management for LYC fishery were lack due to limited data availability. In this study, an Ecopath model was built as the operating model in MSE to evaluate the effects of MPs for the LYC fishery and estimate the LYC ECC in the Min River Estuary to explore the optimal management measure. A total of 12 candidate MPs were identified and tested, including 5 input controls (2 fishing-effort-based and 3 length-based) and 7 catch-based output controls. A 20-year simulation showed that only 4 MPs fully achieved the performance criteria in maintaining biomass and avoiding further overfishing, including curE75 (75 % of current fishing effort levels), minlenLopt1 (the minimum length of retention for maximizing biomass), matlenLim (fishing retention-at-length related to the maturity curve: 100 %) and matlenLim2 (fishing retention-at-length related to the maturity curve: 110 %). The Min River Estuary ecosystem could support up to 17 kg/km2 of LYC. The Ecosim model projects that the LYC biomass increased over 20 % after the application of curE75, and over 37 % with the combination of curE75 and national fishing moratorium policy after the 20-year simulation. The combination of releasing, fishing effort reduction and fishing moratorium is the optimal measure within current management systems for the recovery of LYC fishery in the Min River Estuary. This study provides an ecosystem-based fishery management approach to plan and evaluate restocking programs using data-limited methods and MSE for the LYC and other fisheries.

Characterization of Captive Breeders to Preserve the Residual Genetic Diversity of Adriatic Sturgeon (Acipenser naccarii)

Since 1996, the Adriatic sturgeon (Acipenser naccarii) has been inscribed on the IUCN Red List as “Critically Endangered and possibly extinct in the wild”. Nowadays, its survival totally depends on restocking programs conducted by releasing juveniles generated from adult breeders reared in aquaculture. Conducting accurate genetic characterizations of all individuals potentially involved in reproduction activities is therefore of primary importance to avoid inbreeding and to maximize the genetic diversity transmitted to following generations. Since all animals reared in captivity descend from a single stock of wild origin, this offers the ideal condition for carrying out relatedness analysis based on parentage allocations. In this study, we provided the most complete characterization of about 500 individuals representing the most diverse extant stock of Adriatic sturgeon. Through the analyses of mitochondrial d-loop and 15 microsatellite loci selected from 24 genotyped loci, we identified about 30 different familiar groups, updating data on breeding stocks, increasing the genetic information already available, and extending the analyses to animals never genotyped before. Given its completeness, it will represent a reference database for any future parental allocation of recaptured animals for the inclusion of all other stocks present, as well as for the development of a long-term breeding plan. The approach used has also been proven useful on individuals of unknown genealogy, allowing for the identification of family groups and thus being proven to be promising for the analysis of stocks of other tetraploid sturgeon species.

The Use of Reproductive Indicators for Conservation Purposes: The Case Study of Palinurus elephas in Two Fully Protected Areas and Their Surrounding Zones (Central-Western Mediterranean).

Simple SummaryThe European spiny lobster Palinurus elephas is a species with a high commercial value that inhabits the Mediterranean Sea and the adjacent Atlantic waters and is classified by IUCN as vulnerable due to its continuous overfishing. In this study, we analyse the reproductive parameters of P. elephas populations in two different fully protected areas, including their surrounding commercial zones, in Sardinia (Italy, central-western Mediterranean), where a restocking programme was carried out. Here, data on fecundity, size at maturity, vitellogenin concentration and temporal trends of egg production of P. elephas was provided, and the relevance of this information for fisheries management and conservation planning is discussed.In 1990s, the European spiny lobster Palinurus elephas, one of the most commercially important species in the Mediterranean, exhibited a population decline. For this reason, fully protected areas (FPAs) appeared effective in re-establishing natural populations and supporting fishery-management objectives. Here, the reproductive parameters of P. elephas populations in two different FPAs (Su Pallosu and Buggerru, central-western Mediterranean), where a restocking programme was carried out, and in their surrounding commercial zones, were investigated from quantitative and qualitative perspectives. The comparison of fecundity between females collected inside and outside FPAs did not show statistical differences as well as the vitellogenin concentration, which did not vary among eggs of different size classes of females caught inside and outside the FPAs, indicating the same reproductive potential. The study demonstrated a benefit of overexploited populations in terms of enhancement of egg production overtime (15 years for Su Pallosu and 6 years for Buggerru) with a mean egg production 4.25–5.5 times higher at the end of the study than that observed at the beginning of the study. The main driver of eggs production appeared to be size, with larger lobsters more present inside the FPAs than outside. Given these results, the dominant contribution of the two studied FPAs to the regional lobster reproduction is remarkable.

European Lobster Larval Development and Fitness Under a Temperature Gradient and Ocean Acidification.

Climate change combined with anthropogenic stressors (e.g. overfishing, habitat destruction) may have particularly strong effects on threatened populations of coastal invertebrates. The collapse of the population of European lobster (Homarus gammarus) around Helgoland constitutes a good example and prompted a large-scale restocking program. The question arises if recruitment of remaining natural individuals and program-released specimens could be stunted by ongoing climate change. We examined the joint effect of ocean warming and acidification on survival, development, morphology, energy metabolism and enzymatic antioxidant activity of the larval stages of the European lobster. Larvae from four independent hatches were reared from stage I to III under a gradient of 10 seawater temperatures (13–24°C) combined with moderate (∼470 µatm) and elevated (∼1160 µatm) seawater pCO2 treatments. Those treatments correspond to the shared socio-economic pathways (SSP), SSP1-2.6 and SSP5-8.5 (i.e. the low and the very high greenhouse gas emissions respectively) projected for 2100 by the Intergovernmental Panel on Climate Change. Larvae under the elevated pCO2 treatment had not only lower survival rates, but also significantly smaller rostrum length. However, temperature was the main driver of energy demands with increased oxygen consumption rates and elemental C:N ratio towards warmer temperatures, with a reducing effect on development time. Using this large temperature gradient, we provide a more precise insight on the aerobic thermal window trade-offs of lobster larvae and whether exposure to the worst hypercapnia scenario may narrow it. This may have repercussions on the recruitment of the remaining natural and program-released specimens and thus, in the enhancement success of future lobster stocks.

Movements of Hatchery-Reared Dusky Groupers Released in a Northeast Atlantic Coastal Marine Protected Area

No-take areas are key instruments to promote the effectiveness of Marine Protected Areas (MPAs), particularly concerning the protection of endangered species such as the dusky grouper (Epinephelus marginatus). However, despite the establishment of no-take areas and the prohibition of catching this species in a southwestern Portuguese MPA (SACVMP—‘Sudoeste Alentejano’ and ‘Costa Vicentina’ Marine Park) since 2011, there is still no evidence of population recovery. By using acoustic biotelemetry, this work aimed to evaluate the feasibility of restocking hatchery-reared adult dusky groupers in two no-take areas within the SACVMP. In 2019 and 2021, thirty groupers were tagged with acoustic transmitters and the site attachment and movements of the groupers were assessed in the releasing sites (no-take areas). None of the tagged fish settled down in either of the areas, leaving the no-take areas mainly at dusk and night. Some individuals displayed extended movements of more than a hundred kilometers along the Portuguese coast which was rarely reported for this species. At least in some coastal stretches, those movements were performed close to the shore, which may evidence the importance of coastal MPAs to protect and promote the connectivity of species more associated with rocky reef habitats. Following studies should focus on the conditions that promote site attachment and fidelity by hatchery-reared dusky groupers so that future large-scale restocking programs can be successful in MPAs with appropriate habitats.