Largest Fishery Research Articles

Sustainable Development Strategy Based on Value-Addedin the Fisheries Sector: Study on the Kangean Islands, Sumenep Regency, Indonesia

Objective: Kangean Islands is a group of small islands in Sumenep Regency, East Java Province, Indonesia, which is administratively divided into three sub-districts, namely Arjasa District, Kangayan District, and Sapeken District. This archipelago has very large fisheries potential as seen from its contribution to the Gross Regional Domestic Product (GRDP) of Sumenep Regency, but the utilization of the fisheries sector in this archipelago is still carried out traditionally and tends to be exploitative. This study aims to see the level of sustainability of fisheries sector management and recommend fisheries resource management strategies, in order to increase the economic added value of the fisheries sector and maintain the sustainability of fish resources and the environment in the archipelago. Method: The analytical method used to analyze the degree of sustainability in fisheries resource management in the Kangean Islands is Rapid Appraissal for Fisheries (RAPFISH) with the Multi-Dimensional Scaling (MDS) ordination technique. While the analytical tool used to compile a hierarchy of fisheries sector development strategies to increase economic added value is the Analytical Hierarchy Process (AHP). Results and Discussion: The results of the sustainability analysis in the management of the fisheries sector found that, of the five aspects identified, the results showed that the financial aspect and infrastructure aspect had the category of "Sustainable Sustainability", with values of each aspect of 63.113 and 53.885. While the other three aspects, namely: Human Resources (HR) Aspect, Natural Resources Aspect, and Social Aspect are included in the category of "Less Sustainable". Meanwhile, based on the results of the analysis of the hierarchy of fisheries sector development policies, it shows that the most priority policy to be carried out in the development of a sustainable fisheries sector is the "identification of investment potential and opportunities" program with a priority value of 46%. Furthermore, the strategy that must be chosen is to map the potential of the fisheries sector with a limiting value of 21%. With a Rater Agreement value strength of 0.472727 or 47%, it means that the informants agree in providing an assessment on the paired comparison questionnaire, in determining problems and strategies in the development of the fisheries sector in the archipelago.

Improvement of Immune Defense and Survival of Grouper Fish (Ephinepelus sp.) Using the Immuno-Probiosirkulasi System (SI-PBR) Method in Semi-Intensive Ponds in Brondong, Lamongan

Grouper (Epinephelus sp.) is a marine fishery commodity that is widely cultivated in marine cages and ponds. The export market demand for grouper fish continues to increase every year by 30.75% every year, so there is a need for improvement, through various technological applications. The main obstacle in cultivating grouper fish in ponds is the decline in water quality and disease attacks, which can cause up to 100% crop failure, just 3 – 5 days after infection. One effort that can be implemented is the cultivation method with the Immuno-Probiocirculation System (SIPBR). Brondong sub-district is one of the areas in Lamongan which has large fisheries potential, especially for breakwater water pools, which are the top among other districts. There have been many cases of grouper deaths in ponds to date, which are caused by disease attacks and water quality. The aim of this community service activity is to apply the Immuno-Probioculation System fish aquaculture technology in traditional plus pattern ponds (SI-PBR), increasing grouper fish production in Lamongan Regency, East Java. Observational method which includes socialization / counseling, planning and guidance for implementing SI-PBR technology in one period (three months). These results show positive indications. There is an increase in farmer knowledge, the SI-PBR method can reduce ectoparasite infestation and increase grouper yields from 272.43 kg / ha to 87.66 kg / ha, meaning an increase of 334%. The conclusion from this activity is that the SI-PBR model can increase fish production and can be applied in wider areas in the Lamongan region.

Biological and Fishery Parameters of Jumbo Squid (Dosidicus gigas) in the Colombian Pacific, a Resource without Directed Fishing Exploitation

The distribution range of the jumbo squid (Dosidicus gigas) has increased over the past few decades; it is now found in the entire Eastern Pacific Ocean and is considered an important species in the small and large fisheries of Chile, Perú, Ecuador, Costa Rica and Mexico but not in the Pacific region of Colombia. Three night-fishing campaigns were conducted over a year in the coastal Baudó-San Juan environmental unit, adjacent to the Bajo Baudó Encanto de Manglares Regional Integrated Management District in Chocó, at three locations 20 km, 35 km, and 45 km from the coastline to establish the availability and viability of jumbo squid as an alternative to the target species of artisanal fisheries in the Colombian Pacific. Night fishing sets were conducted at 60 m and 200 m depth at each sampling station to assess some of the biological parameters of the jumbo squid population (mantle length-ML, weight, growth and size at sexual maturity). Most catches were obtained in February and March. Growth was isometric, the average catch size was 24.3 cm ML, size at sexual maturity (L50) was 23.25 cm ML, estimated maximum size (L∞) was 39.9 cm ML, the growth constant (K) was 0.83, and mortality due to experimental fishing was 26 cm ML. According to our results, the jumbo squid fishery in the Colombian Pacific artisanal fishery would be viable during the first months of the year.

The first report of DNA barcoding of commercially important fish in Nias Islands, Indonesia

Abstract. Ramadhaniaty M, Manurung VR, Khairunnisa, Lubis F, Susetya IE. 2024. The first report of DNA barcoding of commercially important fish in Nias Islands, Indonesia. Biodiversitas 25: 742-753. The Nias Islands are an archipelago in the western part of North Sumatera, encompassed by the Indian Ocean, and have become a hotspot for demersal and pelagic fishes. These geographical conditions endow the waters around Nias with large fishery resources, leading to their frequent utilization as fishing grounds for Sumatera Island and its surrounding areas. This research aimed to identify the commercially important fish species with the highest catch frequency in the waters of Nias, and this identification marked the initial stage of the sustainable utilization of fish resources. The method used was DNA Barcoding using genes targeting the COI Mitochondrial locus. Therefore, 43 samples were collected from several North and South Nias fish landing sites. The obtained species were classified into 3 groups based on the commodity type: demersal fish, pelagic fish, and Choncricthyes. There were 8 species of demersal fish (Caesio caerulaurea, Halichoeres scapularis, Lethrinus ornatus, Mulloidichthys flavolineatus, Parupeneus barberinus, Scarus prasiognathos, Plectropomus leopardus, and Variola albimarginata), displaying genetic distances ranging from 0.002-0.275. Pelagic fish consisted of 5 species, namely Amblygaster clupoides, Caranx ignobilis, Caranx sexfasciatus, Ferdauia ferdau, and Scomberomorus commerson, displaying genetic distances ranging from 0.002-0.267. The next commodities were Chondrichthyes with 9 species (Carcharhinus sealei, Himantura leoparda, Neotrygon kuhlii, Paragaleus randalli, Pateobatis jenkinsii, Rhynchobatus cf laevis, Spyrna lewini, Taeniura meyeni, and Urogymnus granulatus), displaying genetic distance ranging from 0-0.271. This value indicates that migratory species such as chondrichthyes have quite extensive movements so that the genetic distance between species and between populations tends to be low.

Coping with crisis: The Peruvian state-owned fishing enterprise Pesca Perú, 1973–1998

This article examines why and how states use the legal and organisational construction of the state-owned enterprise (SOE) to deal with environmental and social crises. In 1973, in response to a drastic collapse in the world’s largest fishery, the Peruvian state nationalised its anchoveta fishing fleet and factories while hastily creating Pesca Perú, an SOE given a monopoly on industrial catch and exploitation of the resource. Pesca Perú struggled with a dual mandate and governments with widely varying ideas of how the Peruvian economy should be organised. In the early 1980s the enterprise lost its production monopoly due as much to environmental factors as to political decisions. It was eventually privatised in the 1990s. While generally regarded as a failed business, Pesca Perú was a useful tool for a state with limited resources to pursue governance and developmental objectives.

Modelling perspective on the climate footprint in south east Australian marine waters and its fisheries

Abstract South eastern Australia is a global warming hotspot, and is also home to ~70% of Australia’s population and one of Australia’s largest fisheries—the South East Scalefish and Shark Fishery. This fishery spans shelf to deep waters, subtropical to temperate waters, employs many gears, and interacts with over 100 species. Despite following best practice fisheries management principles, including taking an ecosystem perspective to overall fisheries interactions, management interventions have failed to arrest or recover the decline of some focal species. Using an Atlantis ecosystem model developed for the fishery over the past 20 years, this paper presents simulations that suggest climate change may be a major contributor to the trajectories seen for a number of species—such as jackass morwong (Nemadactylus macropterus), blue warehou (Seriolella brama), and gemfish (Rexea solandri). This kind of climate influence poses many challenges for fisheries management into the future, raising questions about what to do when climate change undermines or overrides fisheries management actions and objectives.

Kebijakan Pengembangan Perikanan Tangkap Melalui Analisis SWOT Dan Analytic Hierarchy Process (AHP) Di Kabupaten Buleleng, Bali

Buleleng Regency has large fisheries and marine potential, including the capture fisheries sector. Optimal capture fisheries management will be able to provide welfare for community groups that depend on fishing for their lives. This research aims to formulate a policy strategy for the development of capture fisheries in Buleleng Regency. This research was conducted on 15 May - 31 October 2020. The locations for collecting data for respondents were 7 (seven) Districts and 2 (two) Villages in each District in Buleleng Regency. A quantitative descriptive research approach combines SWOT analysis and Analytic Hierarchy Process (AHP). The results of the analysis obtained Progressive Strategy (SO) with a value of x: 0.2 and y: 0.6. This strategy includes the quality of catches, fishing industry areas, coaching and mentoring of fishermen, utilization of fishing ports, fishing business capital, fishing units, and fisherman insurance. The results of the Consistency Ratio (CR) value calculation show a figure of 0.03, which means that the assessment of the strategy criteria is acceptable. The results of the analysis of the policy criteria hierarchy of the Analytic Hierarchy Process (AHP) obtained 5 (five) priority strategies that need to be implemented in collaboration at each level of authority from the Provincial Government of Bali or the Bueleleng Regency Government, namely modernizing fishing units, ensuring the safety and health of fishermen's families through equal distribution of fishermen's insurance receipts, facilitating fishermen's business capital through capital institutions, increasing fishermen's skills and knowledge regarding modernization of technology-based fishing techniques, and utilizing the Sangsit Fish Landing Base (PPI) as the leading center for capture fisheries activities in Buleleng.

Information and Spillovers from Targeting Policy in Peru’s Anchoveta Fishery

This paper establishes that a targeted policy backfires because it reveals information about nontargeted units. In the world’s largest fishery, the regulator attempts to reduce the harvesting of juvenile fish by temporarily closing areas where the share of juvenile catch is high. By combining administrative microdata with biologically richer data from fishing firms, I isolate variation in closures that is due to the regulator’s lower-resolution data. I estimate substantial temporal and spatial spillovers from closures. Closures increase total juvenile catch by 48 percent because closure announcements implicitly signal that fishing before, just outside, and after closures is high productivity. (JEL D83, O13, Q21, Q22, Q28)

Peranan Polisi Republik Indonesia dalam Pemberantasan Praktik Illegal Fishing di Wilayah Perairan Indonesia

Coral reefs owned by the State of Indonesia are approximately 7000 km2 with 480 species of coral that have been successfully described and have a diversity of fish around 1,650 species of fish. Foreign fishermen who often enter Indonesian territorial waters, among others, come from Thailand, Vietnam, the Philippines, and Malaysia. Natuna waters, North Sulawesi waters are the most vulnerable area to illegal fishing activities. The vulnerability of Indonesian waters from illegal fishing activities, in addition to the fact that the water area contains the potential for large fishery resources, also because the geographical position of the Indonesian territorial waters is in international waters so that it is very open to the possibility of foreign fishermen entering Indonesian waters and fishing illegally. Illegal fishing activities still occur in Indonesian waters, despite various efforts to overcome them by the Indonesian government. This cross-border illegal activity is not only a problem for Indonesia, but also an interstate problem considering that the perpetrators and activities are transnational, and therefore, the handling must also be carried out cross-country, especially through bilateral cooperation with neighboring countries in the region where fishermen often enter Indonesian territorial waters illegally. Illegal fishing has become a global concern because this illegal activity has taken place in various regions and is considered to threaten the existence and sustainability of global marine fisheries resources if not handled seriously by the international community. In the study of international relations, illegal fishing can be categorized as a form of transnational crime, because in these illegal activities contained several aspects as included in the definition of transnational crime.

Ecological risk assessment in the southern Indian Ocean: Towards better seabird bycatch mitigation

Abstract Fisheries bycatch has been identified as the most serious threat to many seabird species and there is an increasing awareness of the responsibility of fisheries management bodies to include the impact on non‐target species in their management and regulatory frameworks. In 2022, an ecological risk assessment (ERA) for seabirds and fisheries was presented to the Scientific Committee of the Southern Indian Ocean Fisheries Agreement (SIOFA). This ERA identified 32 seabird species that regularly occurred in the SIOFA Area, of which 11 were determined as being at high risk. This high‐risk group included 10 albatross species that have the greatest likelihood of interacting with SIOFA managed fisheries in Subareas 1, 2 and 3b (west of 40° E) where they overlap with the pelagic longline fishery. Although the pelagic longline fishery for Ruvettus pretiosus is the largest fishery under the auspices of SIOFA, in terms of catch and number of vessels, the existing management measures of SIOFA focused on demersal fisheries and did not include any mitigation requirements for pelagic longlines. In response to the outcomes of the ERA, a proposed amendment to SIOFA's management measures was presented by France to the Meeting of Parties of SIOFA and led to the revision of SIOFA's seabird bycatch mitigation measures in respect of pelagic longlines, making them consistent with those agreed by the Indian Ocean Tuna Commission. Regulatory diffusion, the increased likelihood of adoption of regulation by one agency if that regulation has been adopted by another agency, contributed to the relatively rapid transition from the identification of the risk posed by pelagic longline vessels to the change in regulations to address those risks in SIOFA.

Warm oceans exacerbate Chinook salmon bycatch in the Pacific hake fishery driven by thermal and diel depth‐use behaviours

AbstractFisheries bycatch impacts marine species globally and understanding the underlying ecological and behavioural mechanisms could improve bycatch mitigation and forecasts in novel conditions. Oceans are rapidly warming causing shifts in marine species distributions with unknown, but likely, bycatch consequences. We examined whether thermal and diel depth‐use behaviours influenced bycatch of a keystone species (Chinook salmon; Oncorhynchus tshawytscha, Salmonidae) in the largest fishery on the US West Coast (Pacific hake; Merluccius productus, Merlucciidae) with annual consequences in a warming ocean. We used Generalized Additive Models with 20 years of data including 54,509 hauls from the at‐sea hake fishery spanning Oregon and Washington coasts including genetic information for five salmon populations. Our results demonstrate that Chinook salmon bycatch rates increased in warm ocean years explained by salmon depth‐use behaviours. Chinook salmon typically occupy shallower water column depths compared to hake. However, salmon moved deeper when sea surface temperatures (SSTs) were warm and at night, which increased overlap with hake and exacerbated bycatch rates. We show that night fishing reductions (a voluntary bycatch mitigation strategy) are effective in reducing salmon bycatch in cool SSTs by limiting fishing effort when diel vertical movements bring salmon deeper but becomes less effective in warm SSTs as salmon seek deeper thermal refugia during the day. Thermal and diel behaviours were more pronounced in southern compared with northern salmon populations. We provide mechanistic support that climate change may intensify Chinook salmon bycatch in the hake fishery and demonstrate how an inferential approach can inform bycatch management in a changing world.

Environmental and human facets of the waterweed proliferation in a Vast Tropical Ramsar Wetland-Vembanad Lake System.

The Vembanad Lake and its associated low-lying areas and network of canals (hereafter VBL) form the major part of India's second-largest Ramsar wetland (1512 km2) located in Kerala State alongIndia's southwest coast. The extensive VBL has a large fishery, inland waterways, and popular tourist attractions that support the livelihoods of thousands of people. Over the last several decades, the proliferation of water weeds in the VBL has alarmingly increased, causing many adverse ecological and socioeconomic effects. This study based on a review and synthesis of long-term data introduced the environmental and human dimensions of water weed proliferation in the VBL. Eichhornia (= Pontederia) crassipes, Monochoria vaginalis, Salvinia molesta, Limnocharis flava, Pistia stratiotes, and Hydrilla verticillata are the most troublesome water weeds in the VBL, with the first three being the most widespread. They were mostly imported to India long ago before becoming a part of the VBL.These weeds harmed water quality, waterways, agriculture, fisheries, disease vector management, as well as the vertical and horizontal shrinkage of the VBL through increased siltation and faster ecological succession. The inherently fragile VBL was harmed by extensive and long-term reclamation, the construction of saltwater barrages, and many landfill roads that crisscross water bodies serving as coastal dams, creating water stagnation by blocking natural flushing/ventilation by periodic tides from the adjacent southeastern Arabian Sea. These ecological imbalances were exacerbated by excessive fertiliser use in agricultural areas, as well as the addition of nutrient-rich domestic and municipal sewage, which provided an adequate supply of nutrients and a favourable habitat for the expansion of water weeds. Furthermore, because of recurrent floods and a changing ecology in the VBL, the water weed proliferation has become a more significant problem, with the potential to disrupt their current distribution pattern and spread in the future.

Ship noise quantification of fisheries vessels on the Great Lakes

Prey fish abundances in the Great Lakes are a driver for several agencies’ commitments to the Council of Lake Committees to support fisheries management. These management decisions have profound economic and social impacts within the Great Lakes region. Fisheries estimates done by echosounders or trawling may be biased due to the propagated noise from large fisheries vessels. In the first two years of a four-year collaborative study, crewed fisheries vessels and uncrewed Saildrone vessels were used to compare abundance estimates between “loud” and “quiet” vessels. To quantify the effects of ship noise on prey fish abundance estimates, a mobile ship noise measurement system was designed and deployed to measure radiated acoustic signatures of several ships in the Great Lakes. This talk will discuss the deployment of a mobile underwater acoustic test range and show results of ship noise measurements from the first two years of the program. In addition, plans for future data generation, analysis, and comparison between crewed and autonomous systems will be discussed and an overview of the effects of ship noise on fish avoidance will be discussed in the proceeding talk.

Satellite-Based Analysis of Surface Upwelling in the Sea Adjacent to Zhoushan Islands in China

The fish catch in natural upwelling areas, which accounts for only 0.1% of the ocean surface, accounts for more than 40% of the world’s catch. The Zhoushan fishery, which is the largest fishery in China, is mainly formed by a coastal upwelling that features a low temperature. The upwelling in the study area (29.5–31.5° N, 121.5–123.5° E) is a vital factor affecting the formation of the Zhoushan fishery, and the primary productivity and low temperature that are brought by the rising water are important features of the upwelling. This study used global real-time high-resolution multivariate fused satellite (OSTIA) daily sea surface temperature (SST) data developed by the United Kingdom Meteorological Office that were collected from 1981 to 2020 to explore the spatial and temporal variation of the characteristics of the upwelling phenomenon in the study area. The data were processed by a temperature gradient-based upwelling edge detection algorithm to extract information on the central location of the upwelling, the location clusters in the core area, and the intensity index. The quantities of center and core area clusters were counted for each pixel point, and their corresponding probability values were calculated. The results of the spatial and temporal variation of the characteristics of the upwelling show that the upwelling in the study area was generated in April of each year, increased in intensity, and peaked in August, furthermore, the southern part of the upwelling dissipated in September. The region’s upwelling is spatially oblique and elliptical, with its long axis following the northeast and extending as far as the mouth of the Yangtze River. Its central location and core area were relatively stably existing in Ma’an Archipelago and Zhongjieshan Islands, which was consistent with the location of the two marine pastures in Zhoushan. According to our findings, locations with higher probability values in the upwelling center and core area, where upwelling occurs frequently, are usually accompanied by higher productivity and offer the potential to develop fishing grounds. The insights that were drawn from the study observations can, therefore, provide some reference for future artificial upwelling site selection.

Training on Processing Local Products (Naget Fish) in Improving the Nutritional Status of the Community in Mamboro District, Central Sumba Regency

Fish is a source of animal protein that is consumed by many people because it is relatively easy to obtain and the price is affordable. Attention to low-priced fish and its process into a more expensive food ingredient is what is needed by countries that have large fishery resources, especially in Indonesia. Fish nuggets are food products derived from ground fish with the addition of spices and printed, which is then smeared with coatings (coating and breading), then frying (Rosselinda et al, 2018). Fish nuggets are an alternative to nuggets that contain good nutrition. These fish nuggets contain protein, fat and vitamins which are beneficial to the body and can be used as a side dish for food. Whereas the BUMDes Business Unit is a business entity owned by the Village BUMDes that carries out activities in the economic sector or public services with a legal entity that carries out the functions and objectives of the Village BUMDes. The science of sports nutrition is the application of nutrition to athletes so that they are able to achieve optimal performance.

Sources from Below: A Rebel Archive Rewrites Maritime History of Peru’s Cuarta Región

This paper examines how local archives offer an alternative narrative to the industrial expansion of Peru’s cuarta región: the sea. The rise of Peru’s global fishing economy in the postwar era and the parallel establishment of the 200-mile Exclusive Economic Zone in 1952 added the sea as a new commercial region beyond the rainforest, mountains, and coast. Over the course of the next two decades Peru’s economy would increasingly depend on a small pelagic fish: the anchoveta (Engraulis ringens). Following the anchoveta collapse of 1973, the national economy struggled to rebound and social unrest clotted the coastline. In response to increasing state violence, scientific opacity, and censorship, one notable archive in addition to several smaller collections, emerged to support a rising tide of labor and environmental activism. Drawing from 12-months of archival and ethnographic research and interviews with key stakeholders this article joins the growing interdisciplinary scholarship on archives to develop the concept of “sources from below”: locally-sourced archives that bolster resistance movements and upend hegemonic ontologies of industrial resource exploitation. I pull from postcolonial work on “sciences from below” and political ecology to offer novel insights into human-ocean interactions in the world’s largest fishery. I conclude with lessons for future scholarship on social movements, environmental knowledge, and resource-dependent economies.

Temperature and upwelling dynamics drive market squid (Doryteuthis opalescens) distribution and abundance in the California Current

Abstract Market squid (Doryteuthis opalescens) constitute one of California’s largest fisheries by landings and are an essential prey item for numerous top predators in the California Current ecosystem. However, extreme fluctuations in market squid abundance inhibit our ability to forecast local recruitment. We generate a species distribution model for market squid with data from an annual survey to examine the mechanisms behind the variability in their regional abundance and occurrence. Our results indicate juvenile market squid abundance was controlled by local recruitment in connection with sea surface temperature and upwelling dynamics, with finer spatial variability connected to the extent of upwelling dominated regions. Recent changes in these environmental factors also appear to contribute to the recent northward range expansion of market squid. Our spatiotemporally explicit model estimates of juvenile market squid abundance predicted the occurrence and abundance of older market squid in the diet of California sea lions (Zalophus californianus) and California fishery landings with as much skill as regional survey indices, suggesting the models are robust. Collectively, we provide mechanisms driving market squid variability throughout California’s waters and an ecosystem assessment of this economically and ecologically critical species.

Towards smart government for sustainable fisheries and marine development: An intelligent web-based support system approach in small islands

Indonesia is one of the few archipelagic countries with an abundance of marine resources in the world. However, these characteristics provide different kinds of challenges for remote small island regions in the country, in particular for sustainable development of marine and fisheries. Southeast Maluku Regency also falls into that category. Located in the eastern part of Indonesia, with high biodiversity as it is included in the coral triangle area and flanked by two of the world's largest fisheries, namely the Arafura Sea and the Banda Sea, the region’s marine and fishing sectors still underperform due to the lack of consistency in developing plans. This is due to the limited use of empirical information on the socio-economy, marine characteristics, and empirical potential of the region. This study aimed to build a web-based Intelligent Decision Support System (DSS) for sustainable fisheries and marine development of Southeast Maluku regency and use the system as the basis for evaluation of current and previous region’s marine and fisheries plans. The system provides all the basic to useful calculated information-based GIS (Geographical Information System) in an effort to help local governments better plan and develop the marine and fishing sectors.

Genetic identification and diversity of stocks of the African bonytongue, Heterotis niloticus (Osteoglossiformes: Arapaiminae), in Nigeria, West Africa

Inland fisheries are an important source of protein and income for people in Africa. Their sustainable management can greatly benefit from identification of regional genetic stocks and characterization of their genetic diversity, but such information is lacking for most African freshwater fisheries. The African bonytongue, Heterotis niloticus, is an important component of inland fisheries in West Africa. Nigeria has the largest fishery for African bonytongues, representing ~ 86% of the global total. Recent declines in yields at some Nigerian locations, however, suggest current levels of exploitation may be unsustainable. Habitat degradation also may be impacting some stocks. Despite its commercial and nutritional importance, the African bonytongue has been the subject of scant genetic research to support management. We examined patterns of genetic diversity in natural populations of H. niloticus at four locations in Nigeria, including Kainji Lake, a reservoir on the Niger River in north-central Nigeria, and three southern localities (Ethiope River, Igbokoda River, and Epe Lagoon), as well fish from the Ouémé River delta near Porto Novo, Benin. Eighty-five specimens were genotyped for nine microsatellite-loci. Genetic diversity estimates were highest at Kainji Lake, and substantially lower at southern localities. High levels of genetic differentiation were detected between samples from Kainji Lake and those from southern localities. Low, yet significant FST values were observed among samples from southern Nigerian localities that were more differentiated from the sample from nearby coastal Benin. We thus recommend that African bonytongues from the five locations be considered distinct genetic stocks and managed accordingly.

Growth patterns of larval walleye pollock Gadus chalcogrammus from core and peripheral habitat differ in response to temperature

Walleye pollock (Gadus chalcogrammus) supports one of the world's largest fisheries and is a key species in North Pacific ecosystems. Its future as a sustainable fishery may be dependent on its ability to adapt to changing water temperatures under climate change. The largest global average increase in sea surface temperature has occurred in Alaska, and increasing temperatures are predicted. Here, we examined responses to a range of temperatures in the early life history of walleye pollock from a northern (core) and a southern (peripheral) part of their range using growth measurements and genetics (RADseq). Crosses were conducted to generate families with one female and three male adults from Shelikof Strait, AK and Puget Sound, WA. Offspring were reared to the late larval stage at three temperatures corresponding to low (1.5 °C), medium (5.8 °C), and high (∼12 °C) temperature relative to natural conditions. Alaska pollock outperformed Puget Sound pollock at the lowest temperatures, hatching earlier with a higher growth rate than Puget Sound pollock. At medium temperatures, Puget Sound and Alaska pollock grew at the same rate but Alaska pollock hatched sooner. The response to high temperatures was the same in both groups, characterized by early hatching at a small size and high growth rates. Genetic analysis did not show differences among family groups that survived different temperature treatments. Our results demonstrate local adaptation, although a link between genotype and phenotype was not found.