Wild Stocks Research Articles

Establishment of Wild-Derived Strains of Japanese Quail (Coturnix japonica) in Field and Laboratory Experiments.

Domestic quail are used as both farm and laboratory animals. As the wild ancestor of quails is "endangered," field studies are needed to conserve them. If wild-derived strains of quail are established, they will be unique genetic resources for both farm and laboratory animals. The purpose of the present study was to conduct a field study and create wild-derived quail strains using the breeding stocks in Tokachi, Hokkaido, Japan. Field observations from 2019 to 2022 indicate that wild quails migrate and stay at reproductive sites from late April to late October. Our estimations of the approximate ages of the observed and captured quails imply that adult males have intermittent reproductive opportunities from May to August. Morphological traits collected from adult and juvenile quails in the 2019-2022 population were similar to those previously reported for Japan's 1914 and 1970 populations. Using natural mating of captured wild males and domestic (Dom) females, we established the W50 and W75 strains, which possessed 50% and 75% genetic contributions from the wild stocks. These unique genetic resources can be applied for future conservation and experimental use to understand the domestication history and genetic basis of quantitative traits.

Bioretention filtration prevents acute mortality and reduces chronic toxicity for early life stage coho salmon (Oncorhynchus kisutch) episodically exposed to urban stormwater runoff

As the human population of western North America continues to expand, widespread patterns of urban growth pose increasingly existential threats to certain wild stocks of Pacific salmon and steelhead (Oncorhynchus sp.). Rainfall previously absorbed into the soils of forests and grasslands falls instead on pavement and other hardened surfaces. This creates stormwater runoff that carries toxic metals, oil, and many other contaminants into salmon-bearing habitats. These include freshwater streams where coho salmon (O. kisutch) spawn in gravel beds. Coho salmon embryos develop within a thick eggshell (chorion) for weeks to months before hatching as alevins and ultimately emerging from the gravel as fry. Untreated urban runoff is highly toxic to older coho salmon (freshwater-resident juveniles and adult spawners), but the vulnerability of the earliest life stages remains poorly understood. To address this uncertainty, we fertilized eggs and raised them under an episodic stormwater exposure regimen, using runoff collected from a high-traffic arterial roadway from 15 discrete storm events. We monitored survival and morphological development, as well as molecular markers for contaminant exposure and cardiovascular stress. We also evaluated the benefit of treating runoff with green infrastructure (bioretention filtration) on coho salmon health and survival. Untreated runoff caused subtle sublethal toxicity in pre-hatch embryos with no mortality, followed by high rates of mortality from exposure at hatch. Bioretention filtration removed most measured contaminants (bacteria, dissolved metals, and polycyclic aromatic hydrocarbons), and the treated effluent was considerably less toxic – notably preventing mortality at the alevin stage. Our findings indicate that untreated urban runoff poses an important threat to early life stage coho salmon, in terms of both acute and delayed-in-time mortality. Moreover, while inexpensive management strategies involving bioinfiltration are promising, future green infrastructure effectiveness research should emphasize sublethal metrics for contaminant exposure and adverse health outcomes in salmonids.

Physical Analysis of the Milt in Cultured and Wild Stocks of Scale carp, Cyprinus carpio var. communis

Physical Analysis of the Milt in Cultured and Wild Stocks of Scale carp, Cyprinus carpio var. communis

Value addition and bioprospecting of indigenous ethnic food, Amorphophallus bulbifer (Roxb.) Blume (Araceae) for sustainable livelihood

Tripura, a small hilly state in India, harbors a treasure trove of traditional knowledge that revolves around utilizing forest-based resources for sustenance. Amorphophallus bulbifer (Roxb.) Blume, which belongs to the family Araceae, is a widely available and preferred food choice for the ethnic communities in Tripura. This study aimed to look at its biochemical potential for adding value and for bioprospecting. Several markets and homes were polled to determine how they could be used for more than one thing and to estimate the wild stock, demand, and supply. The results revealed that the corm is processed to make a food cake known as Batema and has a high market value. Batema is a traditional food that is high in carbs and is sold in the local markets which are alternative to soybeans and tofu. Furthermore, the nutritional content analysis reveals that a higher proportion of carbohydrate (7.73%) is present, followed by protein (3.15%), fat (0.05%), and estimated total calories (43.97 kcal/g). Besides that, the number of micronutrients and minerals, viz., Na (26.08%), Mg (0.94%), Al (1.92%), P (1.21%), K (2.99%), and Ca (4.34%), was also estimated. These findings suggested that Batema could be a resource for dietary supplements, which improve the healthfulness of novel foods for human consumption. Unfortunately, this food product is sold locally, which on the contrary, can be revolutionized from its traditional production into large-scale production at the commercial level. Such an approach will help secure livelihoods and increase the production and trade of this unique product.

Artificial Propagation of Indigenous Ornamental Fish Species via Nutritional Manipulation for Stock Enhancement and Conservation as a Step towards Environmental Sustainability: A Review

Indigenous flora and fauna of a particular habitat greatly impacts the environment in maintaining an ecological balance and equilibrium for the normal functioning of the ecosystem as a whole. Native fishes play a major role and holds a major niche in the ecosystem which needs attention at the moment for their conservation and protection, failure of which may prove to be detrimental to the environment. The rapid developmental activities and industrialization taking place currently are leaving a negative impact upon the natural ecosystem. These activities are a major reason for loss of habitat, deterioration, pollution, and degradation. The ornamental fish industry is a budding industry in India and the indigenous fish fauna of the country offers a good market but unfortunately, so far, the requirements and demand are fulfilled from the natural stock through manual collection. Rigorous exploitation of these species may result into loss of species diversity or reduction of stock, provided, anthropogenic causes necessitated by development and industrialization are already acting upon the ecosystem. Therefore, in this review we will discuss the implementation of captive breeding techniques through nutritional manipulation for fish species so that the wild stock is not made vulnerable and instead, the same shall be enhanced through ranching. Though this technique offers certain limitations such as genetical quality compromise, inferior breeding performance etc., nevertheless it still is a major tool in conservational biology. The review will provide insights to researchers on how to achieve captive breeding success by manipulating nutritional component in fishes and eventually with the information made available in this document certain practical implementations may be necessitated which will help us move closer to the broader aspect of biodiversity conservation and sustainability.

Metabolic effects of diet containing blue mussel (Mytilus edulis) and blue mussel-fed salmon in a mouse model of obesity

Alternative feed ingredients for farmed salmon are warranted due to increasing pressure on wild fish stocks. As locally farmed blue mussels may represent an environmentally sustainable substitute with a lower carbon footprint, we aimed to test the potential and safety of substituting fish meal with blue mussel meal in feed for Atlantic salmon. Salmon were fed diets in which fish meal was partially replaced with blue mussel meal in increments, accounting for up to 13.1 % of the ingredients. Fillets from the salmon were subsequently used to prepare obesity-promoting western diets for a 13-weeks mouse feeding trial. In a second mouse trial, we tested the effects of inclusion of up to 8% blue mussel meal directly in a meat-based western diet. Partial replacement of fish meal with blue mussel meal in fish feed preserved the n-3 polyunsaturated fatty acid (PUFA) content in salmon fillets. The observed blue mussel-induced changes in the fatty acid profiles in salmon fillets did not translate into similar changes in the livers of mice that consumed the salmon, and no clear dose-dependent responses were found. The relative levels of the marine n-3 fatty acids, EPA, and DHA were not reduced, and the n-3/n-6 PUFA ratios in livers from all salmon-fed mice were unchanged. The inclusion of blue mussel meal in a meat-based western diet led to a small, but dose-dependent increase in the n-3/n-6 PUFA ratios in mice livers. Diet-induced obesity, glucose intolerance, and hepatic steatosis were unaffected in both mice trials and no blue mussel-induced adverse effects were observed. In conclusion, our results suggest that replacing fish meal with blue mussel meal in salmon feed will not cause adverse effects in those who consume the salmon fillets.

Social and ecological impacts, challenges, and lessons learned from the sandfish sea ranching experience in Maliwaliw Island, Eastern Samar, Philippines

Since the 1970s, Samar and Leyte islands had a thriving sea cucumber fishery but have rapidly declined over the years. In Maliwaliw Island, anecdotal accounts validated by the community revealed that the island had a brisk sea cucumber fishery but collapsed due to uncontrolled collection. In 2013, a sandfish sea ranching project was implemented in Maliwaliw Island, Salcedo, Eastern Samar, to bring back the sandfish that has disappeared from the area, and subsequently provide a supplemental livelihood to the local fishers. This study was conducted to investigate the impacts and lessons learned from the sandfish project. Recruitment of wild stock, increased community knowledge of sea cucumber biology and ecology, additional income through sandfish bycatch, and perceived enhancement of the coastal marine environment of the island were among the positive gains from the project identified by the respondents. On the other hand, poaching by fishers from neighboring communities resulting in inter-community conflicts was a major challenge. Clearly, the sandfish sea ranching project in Maliwaliw achieved ecological, social, and economic impacts on the project participants and the community. However, these gains need to be strengthened with effective management measures including size regulation to sustain the sea cucumber fishery in the area.

Small fish consumption in rural Myanmar.

Assessments of fish consumption are based primarily on data from household surveys that do not capture information on the intra-household distribution of the size or species of fish consumed. Such studies can yield partial or misleading information about the adequacy of aquatic food consumption. We address this gap by focusing on individual-level fish consumption within the household, using data from a survey conducted in a rural part of the Ayeyarwady Region in Myanmar-an area with high levels of fish consumption. We disaggregate fish consumption by the gender of household members and by the quantity, species, and size of fish eaten, estimating quantities of fish consumed using models for reference, to identify gendered patterns of fish consumption at the intrahousehold level. We find higher average levels of fish consumption than reported in previous consumption surveys in Myanmar. Moreover, small fish are consumed more frequently than larger-sized fish. The popularity of small fish species highlights the continued reliance of survey respondents on wild fish stocks, despite all surveyed households also practicing small-scale aquaculture. The average consumption of fresh fish reported by women was 36% lower than that reported by men. Men were more likely to eat large fish species, but women ate more small fish, which may contain higher levels of micronutrients vital for addressing nutrient deficiencies.

Determination of dietary essential fatty acids in a deep-sea fish, the splendid alfonsino Beryx splendens: functional characterization of enzymes involved in long-chain polyunsaturated fatty acid biosynthesis

The splendid alfonsino Beryx splendens is a commercially important deep-sea fish in East Asian countries. Because the wild stock of this species has been declining, there is an urgent need to develop aquaculture systems. In the present study, we investigated the long-chain polyunsaturated fatty acid (LC-PUFA) requirements of B. splendens, which are known as essential dietary components in many carnivorous marine fish species. The fatty acid profiles of the muscles, liver, and stomach contents of B. splendens suggested that it acquires substantial levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from its natural diet. The functional characterization of a fatty acid desaturase (Fads2) and three elongases (Elovl5, Elovl4a, and Elovl4b) from B. splendens confirmed their enzymatic capabilities in LC-PUFA biosynthesis. Fads2 showed Δ6 and Δ8 bifunctional desaturase activities. Elovl5 showed preferential elongase activities toward C18 and C20 PUFA substrates, whereas Elovl4a and Elovl4b showed activities toward various C18-22 substrates. Given that Fads2 showed no Δ5 desaturase activity and no other fads-like sequence was found in the B. splendens genome, EPA and arachidonic acid cannot be synthesized from C18 precursors; hence, they can be categorized as dietary essential fatty acids in B. splendens. EPA can be converted into DHA in B. splendens via the so-called Sprecher pathway. However, given that fads2 is only expressed in the brain, it is unlikely that the capacity of B. splendens to biosynthesize DHA from EPA can fulfill its physiological requirements. These results will be useful to researchers developing B. splendens aquaculture methods.

A decadal outlook for global aquaculture

A decadal outlook for global aquaculture

The Genetic Composition of Wild Steelhead Based on Spatial Proximity to a Hatchery

AbstractManagement of hatchery and wild stocks of steelhead Oncorhynchus mykiss within the same watershed requires careful consideration when management objectives include the use of the hatchery stock to meet fishery objectives while maintaining the genetic integrity of coexisting wild stocks. This scenario can be further complicated when management objectives for the hatchery stock include supplementation of natural production. The lower Clearwater River in Idaho provided an ideal location to evaluate hatchery steelhead genetic influence within a drainage with separate wild steelhead and supplementation management emphasis areas. We collected 813 genetic samples from wild juvenile steelhead from two sample years in 10 tributaries to the lower Clearwater River to explore genetic structure and assess hatchery influence. Overall, levels of genetic diversity of wild groups were comparable with those observed elsewhere in the Snake River basin. Estimates of effective population size of sample tributaries ranged from 22 to 198 spawners, with a median of 84. All but two tributaries had >50 spawners, and evidence of natural gene flow from other stocks was observed. Results of the study display three zones of hatchery influence in the lower Clearwater River: (1) no influence in lower tributaries with wild steelhead emphasis, (2) moderate influence in wild steelhead tributaries in close proximity to the hatchery facility, and (3) significant influence in hatchery‐supplementation tributaries. Interestingly, a number of wild steelhead reporting groups from elsewhere in the Snake River basin were observed in the assignments of study fish, suggesting movement of wild steelhead among larger drainage areas. Techniques outlined in this study can be used to monitor future hatchery influence in the Clearwater River drainage, track historic versus contemporary genetic influence in the drainage, and apply to other watersheds with hatchery and wild steelhead management objectives.

Effect of Enriched Substrate on the Growth of the Sea Cucumber Holothuria arguinensis Koehler and Vaney, 1906 Juveniles

The sea cucumber Holothuria arguinensis (Koehler and Vaney, 1906) presents an increasing commercial value in Asian markets and its exportation depends exclusively on wild stock harvesting. Production through aquaculture has been acknowledged as an alternative to supply demand and reduce pressure on natural stocks, but there are still bottlenecks to overcome, such as low growth rate and survival. This study focuses on the evaluation of the growth of juveniles of H. arguinensis through substrate enrichment—direct mixing of Sargassum vulgare with sediment—in recirculating aquaculture systems (RAS), for 4 months, with a baseline diet of Saccorhiza polyschides. Compared to the control (no enrichment), sea cucumbers fed with enriched sediment showed the highest specific growth rate (SGR), the highest growth rate (GR) and the lowest size heterogeneity. The results obtained in this study showed a favorable growth of sea cucumbers when in the presence of a substrate enriched with Sargassum vulgare, representing an important step towards the viability of large-scale sea cucumber rearing in Europe.

Artificial Propagation of Pomadasys hasta (Bloch, 1790): A Key to Reach Sustainable Aquaculture

Reproduction of Pomadasys hasta was studied in captivity to establish an induced breeding protocol and larvae rearing tactics. Three distinct hormones viz., human chorionic gonadotropin (HCG), luteinizing hormone-releasing hormone analogues (LHRHa) and salmon gonadotropin hormone-releasing hormone (S-GnRHa) were injected to matured brooders in treatment 1 (T1), treatment 2 (T2) and treatment 3 (T3) but only 0.9% NaCl used in T4 as a control. In each treatment, three experimental trails, E1 (♀40:♂20 µg.kg-1), E2 (♀50:♂25 µg.kg-1) and E3 (♀60:♂30 µg.kg-1) were conducted along with three replications of each trail in order to optimize the hormone dose for the target species. The obtained results have aroused much attention as this is the first breakthrough on induced breeding of a grunter in the Indian subcontinent. Variation in fertilization rate, latency period, egg output and hatching rate in response to different treatments and trails were revealed here. Spawning was occurred between 33-48 h of injection in all the experiments at 17-25°C water temperature. Above all, the highest fertilization (95.45±2.34) and hatching (75.45±4.07) rates were observed in E2 of T2. After 22-26 h of fertilization, the larvae emerged from the egg membrane and the newly hatched larvae were 1.6-1.8 mm in length. Turning larvae into juveniles was noticed by 40–45 days post-hatch (dph) with scales on the entire body surface. The total length was recorded as 43.5±2.1 mm and average body weight as 0.7±0.2 g at 95 dph. This investigation unlocked a track for producing seed of P. hasta in a commercial hatchery for a sustainable aquaculture without hampering their wild stock.

A novel decision-support system for augmenting sustainable lobster production through comparison of mariculture systems at increasing stages of technological development

In the face of depleting wild stocks of lobster globally, mariculture is widely viewed as a technology for enhancing production, resource efficiency, economics, and effective management of dwindling stocks while supporting livelihood security. We used a novel multi-stage experimental strategy followed by robust non-linear growth model simulations for establishing a Decision-Support System (DSS) to foster sustainable and cleaner production practices in lobster mariculture. The strategies explored in the first stage, which dealt with rearing lobsters in sea cages at increasing levels of technological development, significantly enhanced lobster production and thus, culture system productivity 5.9 times over unsustainable conventional systems. Growth performance, feed utilization, and survivability of lobsters were found to be significantly ameliorated in culture setup-3 (P ≤ 0.01), which was the most technologically advanced setup. In the second stage, non-linear models were fit to growth curves, and the best-fit models were used for the prediction of lobster biological metrics in the mariculture systems. These predictions were then validated using in-situ allometric traits. The DSS thus developed can effectively aid decision-making to optimize culture duration, stock condition, feed optimization, and harvest size to maximise economic returns from lobster mariculture while ensuring sustainability.

Analysis of post-maturation biochemical changes in the thalli of Phycocalidia vietnamensis (Bangiales) occurring in the wild stock

Analysis of post-maturation biochemical changes in the thalli of Phycocalidia vietnamensis (Bangiales) occurring in the wild stock

Hatchery supplementation increases potential spawning stock of Rio Grande Silvery Minnow after population bottlenecks

AbstractObjectiveSupplementation of imperiled wild fish stocks with captively raised fish is a commonly used conservation tool. Programs designed to maintain or improve fish populations through supplementation should be evaluated to determine whether they are meeting conservation objectives. The Rio Grande Silvery Minnow Hybognathus amarus is a small‐bodied, endangered minnow endemic to the Rio Grande basin of the southwestern United States. The wild population of Rio Grande Silvery Minnow has been supplemented with captive‐reared fish since 2002. Our objective was to determine whether supplementation measurably increases the number of spawning fish after years of population bottlenecks; this objective was simplified because nearly all hatchery‐released fish have been given identifying markings.MethodsWe leveraged a long‐term fish sampling data set (18 years) covering the species' contemporary range and a single‐season, high spatial coverage fish sampling data set to determine whether the number of potential spawners was increased by the addition of hatchery fish.ResultHatchery‐reared fish increased the catch rates of spawners by up to an order of magnitude in some years. We also observed that most hatchery‐reared fish were recaptured near the point of release. We were able to determine that supplementation with hatchery fish increased the abundance and distribution of Rio Grande Silvery Minnow and provided the desired demographic boost after severe population bottlenecks.ConclusionReleasing hatchery‐reared fish may be a useful tool for conservation of imperiled freshwater fishes. However, there is a need for spawning and rearing infrastructure that matches the life‐history of the species and sufficient postrelease monitoring to evaluate the effectiveness of hatchery supplementation. Use of hatchery‐reared fish has been beneficial for improving population resiliency of Rio Grande Silvery Minnow following recruitment bottlenecks; however, natural recruitment can greatly exceed hatchery supplementation and conditions promoting natural recruitment should be restored.

Comparison of fatty acid composition of the eggs of wild and farmed Coregonus maraena and the influence of feed

Abstract The fatty acid (FA) compositions of eggs from wild whitefish and captive broodstocks were investigated to estimate the FA requirements of Coregonus maraena. The aim of this study was to increase basic knowledge on the nutritional needs of broodstock. Whitefish eggs from two natural spawning grounds were compared with that of captive broodstocks that were fed three commercially available feeds used in fish farms in Mecklenburg-Vorpommern, Germany. Wild fish eggs differed significantly in crude protein content and FA profiles from the eggs of experimentally farmed fish groups. The percentage of monounsaturated FAs (MUFA) were significantly lower in the wild fish eggs. The most common MUFA was oleic acid in all groups, although in the wild fish eggs the value of it was almost half of that in farmed fish eggs. Wild fish eggs had significantly higher values of total polyunsaturated FAs (PUFA), especially of n-3 PUFA, which was nearly double that of the eggs of the farmed fish groups. Additionally, it was shown that egg FA composition even differed between the wild fish stocks that were from the same area, whereas there were no differences in egg proximate composition or FA composition among the three feeding groups even though the compositions of the feeds fed to these fish differed significantly. The present study suggested that the proportions of essential FAs supplied in the dry feeds fed to the captive broodstocks were inappropriate for this species, and feeds must be adapted further to meet the nutritional requirements of this species to improve the quality of farmed whitefish eggs.

Sanctioned Quotas Versus Information Provisioning for Community Wildlife Conservation in Zimbabwe: A Framed Field Experiment Approach

We investigate the behavioural responses of natural common-pool resource users to three policy interventions—sanctioned quotas, information provisioning, and a combination of both. We focus on situations in which users find utility in multiple resources (pastures and wild animal stocks) that all stem from the same ecosystem with complex dynamics, and management could trigger a regime shift, drastically altering resource regrowth. We performed a framed field experiment with 384 villagers from communities managing common-pool wildlife in Zimbabwe. We find that user groups are likely to manage these natural resources more efficiently when facing a policy intervention (either a sanctioned quota, receiving information about a drastic drop in the stocks’ regrowth below a threshold, or a combination of both), compared to groups facing no intervention. A sanctioned quota is likely to perform better than providing information about the existence of a threshold. However, having information about the threshold also leads to higher efficiency and fewer depletion cases, compared to a situation without any intervention. The main contribution of this study is to provide insights that can inform policymakers and development practitioners about the performance of concrete and feasible policy interventions for community wildlife conservation in Southern Africa.

The wedge clam (Donax trunculus) hand-operated fishery in the NW Mediterranean Sea: Landings, catch composition, damage rates and impact of fishing activity

The bivalve wedge clam Donax trunculus is a highly valued species in Spain, but wild stocks have decreased in the Mediterranean region in recent decades. Internal demand exceeds the existing supply derived from local production. Hand-operated dredge fishery is still important in some coastal areas of Spain, such as the Ebro Delta (NE Spain). However, scientific information is lacking on most aspects of this fishery which is essential for its sustainable management. In this context, this study aimed to provide the first characterization of the hand-operated dredges fishery; evaluate the damage of this fishery on the megabenthic fauna; and analyze the impact of the fishing activity on the wedge clam. Our results indicate that landings declined dramatically since the mid-1990s and the main causes for this decline are postulated. Fishing effort was highly seasonal, being more intense from March to September. The discard fraction was very small (5.74% in abundance and the 3.74% in biomass) and 61.93% of the discards did not suffer damage. Clam fishing activity had an impact on recruit density in the short term (3 months), but not on recruit size and commercial fraction density, biomass and size. Our results provide tools for a better management of this type of fisheries.

Estimation of dietary protein and energy requirements of doctor fish, Garra rufa, using a bioenergetic factorial approach

The use of doctor fish, Garra rufa, is widening in the treatment of psoriasis and in recreational spas all over the world. The increasing demand for the fish has created pressure on its wild stocks, making its rearing in captivity necessary. However, there is no specifically formulated diet meeting the dietary nutrient requirements of doctor fish at different developmental stages. The present study was planned to estimate the dietary protein and energy requirements of doctor fish based on a factorial approach. Two growth experiments were conducted using fish with initial mean weights of 0.46 g (small) and 0.84 g (large) at various feeding levels to estimate the maintenance requirements of energy and protein and their utilization efficiencies. Metabolic body weight (BW) exponents for energy and protein were estimated from a starvation study as 0.81 and 0.67, not significantly different from the largely accepted values of 0.80 and 0.70, respectively (P > 0.05). The maintenance requirements of digestible energy (DE) and digestible protein (DP) were 55.5 (kJ/kg BW0.80/day) and 0.49 DP g/kg BW0.70/day, and the utilization efficiencies of DE and DP were 0.61 and 0.35, respectively. Dietary DP:DE demands decreased as fish size increased. The key sizes of fish for changing DP:DE requirements were estimated with one and two-break point analysis. Based on those estimated critical sizes, two hypothetical diet specifications were provided for doctor fish weighing between 0.1 g and 5.0 g. A video shooting study carried out to measure the fish’s nibbling behavior showed a strong influence of feeding level (P < 0.05) where the lowest feeding level (21 kJ/kg BW0.80/day) induced fish to longer skin feeding behavior. The findings of the study allow the creation of specific doctor fish diet formulations for their cultivation and maintenance in spas and health centers.