Ecological, environmental and socioeconomic aspects of the Lake Victoria's introduced Nile perch fishery in relation to the native fisheries and the species culture potential: lessons to learn

Inland fishery ecosystems in Africa are characterized by patterns of overexploitation, environmental degradation and exotic species introductions. Ecological complexity and diversity of aquatic habitats dictate that fishes in general are not evenly distributed in a water body. However, fisheries management regimes tend to ignore this basic principle, assume generalized conditions in a water body, and focus more on ‘desired’ objectives such as maximizing catch. The result is to disregard fish habitat boundaries and anthropogenic influences from the catchment that influence fish production. Overexploitation and environmental degradation disrupt sustainable socioeconomic benefits from the fisheries, create uncertainty among investors, but leave some managers calling for more information with the expectation that the fisheries will recover with time. Open access to the fisheries and full control of fishing effort remain challenges for managers. Exotic species introductions and fish farming can increase production, but such interventions require firm commitment to sound ecological principles and strict enforcement of recommended conservation and co‐management measures in capture fisheries. The general tendency to downplay fishing effort issues, other ecosystem values and functions or rely on temperate fisheries models until a new cycle of overexploitation emerges, characterizes many management patterns in inland fisheries. Aquaculture is not an option to challenges in capture fisheries management. Aquaculture should be developed to increase fish production but even this practice may have negative environmental impacts depending on practice and scale. Decades of information on Lake Victoria fisheries trends and aquaculture development did not stop the collapse of native fisheries. The successfully introduced Nile perch (Lates niloticus) has shown signs of overexploitation and aquaculture has again been considered as the option. By reviewing significant trends associated with Nile perch and its feasibility in aquaculture this paper uses Lake Victoria to illustrate ‘special interest management’ targeting selected species of fish rather than the fisheries.     

Acoustic fish biomass assessment in a deep Tunisian reservoir: effects of season and diel rhythm on survey results

To determine the best acoustic sampling period for obtaining fish biomass estimates of a Mediterranean deep reservoir in Tunisia, day and night surveys were performed in spring (April), summer (September), autumn (December) and winter (March). A Simrad EK60 echosounder, equipped with two 120 kHz split-beam transducers for simultaneous horizontal and vertical beaming, was used to sample the entire water column. Data collected in December were not usable, because fish merged with methane gas bubbles. However, fish abundance varied across the other seasons, with a peak in acoustic biomass during summer nighttime hours associated with high water temperatures. Across seasons, the fish occupied the entire water column and fish schools were rarely observed. The preferential timeframe (i.e. maximum fish detectability and low gas flux) for acoustic sampling was nighttime hours in summer and daytime hours during spring and winter. Our findings highlight the importance of collecting data across seasons and photoperiods when determining an acoustic sampling strategy.     

Legal and Policy Dimensions of Coastal Zone Monitoring and Control: The Case in Ghana

Ghana is implementing a monitoring control and surveillance (MCS) system, which works within the network of the global position system (GPS), and is intended to provide an integrated ocean-monitoring regime and to enhance the capacity of the nation to effectively protect and utilize its ocean resources. This article reviews the need for and importance of the MCS system for Ghana. In addition, this article looks at the issues raised by the implementation of a MCS system in the context of coastal states' rights and the rights of other users of the sea.­     

Development of a Fish Based Lake Typology for Natural Austrian Lakes >50 ha Based on the Reconstructed Historical Fish Communities

Based on the reconstructed native fish communities all natural Austrian lakes >50 ha (n = 43) were classified into four groups using cluster analysis methods. Sentinel species (i.e. species with highest discriminating value for lake types and characteristic for a specific lake group) and type specific fish species (accompanying species with additional value for characterising lake groups) were defined by a newly developed index and by similarity analysis. The first group included 16 lakes of high altitude, small surface area and low fish species number with arctic char as a sentinel species. The second group (n = 10) was characterized by intermediate altitude, large surface area and high maximum water depth with the minnow as sentinel species. The third group contained 14 lakes with low maximum water depths and a long retention time. For this group the bleak was found as a sentinel species. The lakes of the eastern part of Austria represented the last group (n = 3) and were characterized by low altitude and very shallow water depth with pike‐perch as a sentinel species. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The cost to government of maintaining a commercially unviable fishery: The case of newfoundland 1981/82 to 1990/91

The commercial fishery for northern cod off Newfoundland has been closed since 1992. Since then, the recreational “food fishery”; has also been closed, as have the fisheries for many additional cod and other groundfish stocks. The Newfoundland fisheries had been commercially unviable for many years before the closures. This article records the federal and provincial governments’ financial outlays (expenditures, transfer payments to individuals, subsidies, net equity purchases, and net loans) on the fishery during the decade following 1981. Special emphasis is placed on the cost of the financial restructuring of the industry in the mid‐1980s, net unemployment insurance payments, and social overhead capital expenditures.     

The mangrove-based coastal and nearshore fisheries of Bangladesh: ecology,exploitation and management

The mangrove forest of Bangladesh, the largest continuous mangrove forest of the world, is one of the most important coastal features of the country. The existence of the mangrove has increased the values of other coastal and marine resources such as the coastal and marine fisheries by increasing productivity and supporting a wide biological diversity. The artisanal fishery, which is highly influenced by mangroves, has been contributing 85–95% of the total coastal and marine catch of Bangladesh. The mangrove also supports offshore and deep sea fisheries by playing a significant role as nursery ground for many deep sea fishes and shrimps including the giant tiger shrimp (Penaeus monodon) which is the major species of the industrial bottom trawl fishery of Bangladesh. The mangrove also contributes significantly in shrimp farming which has been the most significant export-oriented industry since the 1970s. However, the mangrove fisheries have been under intensive pressure from deleterious fishing activities and deliberate aquaculture development by destructing mangrove habitats. The impacts of mangrove have been reflected in the contribution of artisanal fishery catch that has been in a continuous decline since the 1980s. Shrimp farming has been the most destructive contributor to mangrove destruction with a corresponding loss of biological resources particularly the wild shrimp fishery. This paper reviews different aspects of the mangrove fisheries of Bangladesh and discusses the impacts of different fisheries. The paper identifies the importance of reviewing, amending and/or replacing the traditional management approaches by the new management techniques such as habitat restoration and stock enhancement in the natural environment; the paper also identifies the need for research findings in formulating and implementing new management approaches.     

A Cover Story: Fisheries May Drive Stocks to Extinction

The cover of the 1993 reprint of Beverton and Holt's book bears a diagram, its significance previously unrecognized, that expresses extinction due to fishing. This paper traces the concept to self-regenerating yield models in their 1957 book, its numerical development therein far in advance of its reinvention 30 years later. Local extinction constitutes a critical impact of fisheries on aquatic ecosystems that has been too often downplayed by fisheries science.     

Fisheries Certification in Russia: The Emergence of Nonstate Authority in a Postcommunist Economy

Market-based incentives are a new approach to direct fisheries toward greater sustainability. The Marine Stewardship Council (MSC) is the leading certification scheme for wild capture fisheries. Four Russian fisheries were certified from 2010 to 2014. Despite a slow start, the Russian fishery assessments have gone more quickly, received less public criticism, and scored better over time. Consensus is emerging that the Russian system for fisheries management fulfills the MSC requirements.     

On the Spinicaudata (Branchiopoda) from Lake Cuitzeo,Michoacán,México: First report of a clam shrimp fishery

Cuitzeo is the second largest lake in México (ca. 425 km²). Indigenous people collect clam shrimp (locally known as `conchilla') and sell them dry as pets' food; the income is important for the local economy. To our knowledge, this is the first report of a clam shrimp fishery. Two conchilla species co-occur: Eocyzicus digueti (Richard) and Leptestheria compleximanus (Packard). They were restricted to the saline, soda-alkaline, and temporally astatic W and NW portions of the lake. E. digueti constituted 70% of the total clam shrimp abundance, and L. compleximanus the remainder. Populations were dominated by juveniles, followed by females and males, with sex ratios (male:female) of 1:1.2 to 1:1.4. E. digueti was larger (3–11 mm) than L. compleximanus (3–8.5 mm), and males were larger than females in both species. There were highly significant correlations between carapace size and the number of growth lines and carapace size and the number of eggs. Although previously reported from México, both species are new records for Lake Cuitzeo and for Michoacán state.     

Length‐weight relationships of three indigenous fish species from National Nature Reserve for Rare and Endemic Fishes of the upper Yangtze River,China

Length‐weight relationships (LWRs) were estimated for three small indigenous fish species, (Sinogastromyzon szechuanensis, Sinogastromyzon sichangensis and Sinocrossocheilus labiatus) in the upper Yangtze River, China. Samples were collected using three types of local traditional fishing gears, including gill nets (mesh size: 1 cm), fish cages (mesh size: 0.5 cm), and electrofishing techniques (CWB‐2000 P, 12V, 250 Hz), in April, July and October 2013 and 2014, and April and October 2016. The sample size for each species were gathered separately, with 100 for S. szechuanensis, 381 for S. sichangensis and 49 for S. labiatus from National Nature Reserve for rare and endemic fishes of the upper Yangtze River, China. The length‐weight relationship parameter values of b were calculated as 2.986 for S. szechuanensis (b: 2.854–3.118), and 3.284 for S. sichangensis (b: 3.209–3.359) and 3.119 for S. labiatus (b: 2.911–3.326). The primary data will be meaningful for further research about sustainable development and scientific management of fishery resources of the upper Yangtze River.     

Length–weight relationships for five fish species from the middle reaches of the Yangtze River,China

Length–weight relationships (LWRs) for five fish species which were captured by trap‐nets and gillnets (major mesh size: 1–10 cm) from the middle Yangtze River, China (29°47′ – 29°26′N; 112°51′ – 113°08′E) were determined in September 2017. These were Acheilognathus hypselonotus (Bleeker, 1871), Culter oxycephaloides Kreyenberg & Pappenheim, 1908, Distoechodon tumirostris Peters, 1881, Sarcocheilichthys nigripinnis (Günther, 1873) and Micropercops swinhonis (Günther, 1873). The LWRs were estimated using the logarithmic form of the formula W  =  a  ×  L^b. The b value ranged from 2.879 for A. hypselonotus to 3.285 for M. swinhonis. LWRs for four fish species and new maximum lengths for three species are presented to FishBase for the first time.     

Records of a lake's life in time: the sediments

The evidence from analysis of cores from lake sediments is used to identify the influences which, acting through time, have brought about changes in the lakes of the English Lake District. These are: i. climatic changes, recorded mainly in microfossil assemblages ii. soil dynamics on catchments — the natural soil development of an interglacial cycle and its effect on water composition, and iii. perturbations of input resulting from activities of man.The present position of each of 14 lakes in a series of increasing eutrophication is shown to be the result of two processes of modification by man. The first was a significant reduction in volume of the hypolimnion of the shallow lakes, consequent on the accelerated rate of sediment accumulation which followed deforestation and cultivation of catchments in all the lakes — this did not affect the biology of the deep lakes. The second has been the introduction of human and animal wastes into some of the lakes during the last 120 years, which imposed on affected lakes a process of more rapid change which was more intense in the shallow lakes.     

Omega-3 Fatty Acids in Fish from the Laurentian Great Lakes Tribal Fisheries

Dietary fish must be assessed for benefits and risks to formulate risk management strategies. This article demonstrates that Laurentian Great Lakes (GL) freshwater species are good sources of omega-3 fatty acids using new data from a small sample (n = 7) of Lake Superior siscowet lake trout (Salvelinus namaycush siscowet) and five other GL fish species’ data. For Lake Superior (LS) siscowets, the saturates, mono-unsaturates, and poly-unsaturates composed 20.1, 40.7, and 39.1% of total lipid weight, respectively. Omega-3 poly-unsaturates (PUFAs) in these fish were more than twice the omega-6 (omega 3/6 ratio = 2.4). The LS lake trout data were combined with earlier LS data collected during the 1980s for eight other species and from five species of Lake Erie fish. All the GL freshwater species were compared with seven other published marine and freshwater fish studies from other global regions. PUFAs were compared based on latitude and marine versus freshwater origin. Differences between marine and freshwater species in omega-3 fatty acid were less at higher latitudes. GL freshwater fish species can be a good source of beneficial fats like marine fish and must be accounted in effective risk communications involving persistent bioaccumulative toxicants in dietary fish.     

Taking account of fish welfare: lessons from aquaculture

This paper explores the possibility that lessons learned from aquaculture might contribute to current debate on welfare and fisheries. After looking briefly at the history of research interest in the welfare of farmed fishes, some implications of using different definitions of and approaches to the concept of welfare are discussed. Consideration is given to the way in which the aquaculture industry has responded to public concern about fish welfare and, for cases where these responses have been effective, why this might be the case. Finally, possible cross‐over points between aquaculture and fisheries in the context of fish welfare, as well as experience and expertise that might be shared between these two areas, are identified.     

From the Desk of the Editor-in-Chief

The current problems involving Spain's oversized fishing fleet are explained by the growth of the fleet throughout the 20th Century. This article reviews the birth and development of Spain's distant-water fishing fleet that led to it becoming one of the world's largest fleets, albeit a fleet now devoid of fishing grounds, following the implementation throughout the world of the 200-mile exclusive economic zone.     

Fort Peck paddlefish population survival and abundance in the Missouri River

Excessive fishing pressure can induce population declines or complete collapse of fisheries. Unless commercial and recreational fisheries for K-selected fishes, or those with slow growth and late maturation, are carefully managed, declines in abundance or fishery collapse is probable. Paddlefish Polyodon spathula,are a K-selected species that experienced historical declines in abundance as a result of habitat degradation and overfishing. Mark-recapture studies are well-suited for long-lived fishes by providing information on population density and vital rates. For sustainable commercial or recreational fisheries targeting species such as the paddlefish, managers require accurate estimates of population vital rates including survival, abundance, and exploitation. We used a Montana Fish, Wildlife & Parks (MFWP) mark-recapture dataset and modified Jolly-Seber (POPAN) models to estimate survival, recapture, probability of entry, and abundance of 8,518 tagged paddlefish over a 25-year period. With many supporting estimates including stable survival (0.92 for females, mean of 0.82 for males), low exploitation rates (means of 2.6% for females and 2.9% for males), and stable abundance estimates (25-year mean of 12,309 individuals for both sexes), the Fort Peck paddlefish population appears to be stable and well-managed over the past 25 years. Presently, this is the only study focused on paddlefish in North America that has estimated survival and abundance for both male and female paddlefish using contemporary analyses. This research provided a unique opportunity to highlight that the effort exerted by management agencies to collect long-term field data is extremely useful to our understanding of fish populations and management.     

The Politics of Managing the Maine Lobster Industry: 1860 to the Present

Marine fisheries are in a state of crisis. One of the few successfully managed fisheries is the Maine lobster industry where catches are at an all time high. An important factor in this success is the effectiveness of regulations which were developed during three periods over the course of the past 125 years. In all cases, the regulations are the result of heavy lobbying activity by various factions in the industry. Both strong commercial rivalry and genuine concern for the well-being of the lobster resource played a role in generating these regulations. However, history did not repeat itself. In each period, the players, circumstances, and goals were very different. The result, however, is a set of effective regulations which are largely self-enforcing.     

Recruitment models: diagnosis and prognosis

Probabilistic projections of future fishpopulation dynamics and the determination ofmany management reference points are bothdriven by fishery recruitment models. In turn,these projections and reference points largelygovern perceptions of the likely response of apopulation to fishery management action. Hence, recruitment modeling is a vitalcomponent of stock assessment as carried outfor the purposes of strategic fisheriesmanagement. This review presents a synopsis ofthe types of recruitment model that arecurrently utilised in stock assessments, thereasons that certain models are habituallyselected and the problems inherent in theiruse, and some of the key ongoing researchefforts that are attempting to improve thevalidity of recruitment models. The need forincreased multidisciplinary symbiosis in thedevelopment of recruitment models isemphasized.     

Applications of DNA barcoding to fish landings: authentication and diversity assessment

DNA barcoding methodologies are being increasingly applied not only for scientific purposes but also for diverse real-life uses. Fisheries assessment is a potential niche for DNA barcoding, which serves for species authentication and may also be used for estimating within-population genetic diversity of exploited fish. Analysis of single-sequence barcodes has been proposed as a shortcut for measuring diversity in addition to the original purpose of species identification. Here we explore the relative utility of different mitochondrial sequences (12S rDNA, COI, cyt b, and D-Loop) for application as barcodes in fisheries sciences, using as case studies two marine and two freshwater catches of contrasting diversity levels. Ambiguous catch identification from COI and cyt b was observed. In some cases this could be attributed to duplicated names in databases, but in others it could be due to mitochondrial introgression between closely related species that may obscure species assignation from mtDNA. This last problem could be solved using a combination of mitochondrial and nuclear genes. We suggest to simultaneously analyze one conserved and one more polymorphic gene to identify species and assess diversity in fish catches.