Resilient recreational fisheries or prone to collapse? A decade of research on the science and management of recreational fisheries

Are recreational fisheries resilient to harvest or prone to collapse? This paper reviews research published since that question was posed by Post et al. (2002, Fisheries 27 , 6–17). A number of patterns and processes have been identified that suggest understanding the risk of collapse requires knowledge of the fishing effort response, degree of depensation in the fishery and the life history of the harvested species. Processes involving the behaviour of fish, behaviour of anglers and management responses to declining quality can all impact the degree of resilience of recreational fisheries and their risk of collapse. The spatial context of an individual fishery can be important as they are often embedded in lake districts and joined by mobile anglers so their local dynamics are not independent from other fisheries. Typical regulations that restrict the behaviour of individual anglers in open‐access fisheries can provide some resilience but cannot prevent collapse if the fishing effort is too high. Many uncertainties remain related to the occurrence and intensity of the key processes and therefore adopting an adaptive experimental management approach might be the most useful approach to minimise the risk of collapse in recreational fisheries.     

Reconciling sustainability,economic efficiency and equity in fisheries: the one that got away?

Concern about the global state of fisheries and fish resources has highlighted the three primary considerations in fisheries management: sustainable utilisation, economic efficiency and equity in access to resources. We appear to be failing in pursuit of all three goals. Living marine resources are particularly threatened by overfishing, leading to many of the world’s fish stocks being heavily, fully or over exploited. Similarly, the economic diagnosis is that costs of fishing exceeded the value of the world’s catch by about US$ 40 billion at the beginning of the decade. Statistics on equity are less available, but the necessary spread of limited access to fisheries frequently has the greatest impact on the small scale, traditional fisher. This paper considers the reasons underlying the general failure of fisheries management and the solutions that are being proposed. Factors contributing to the problems include high biological uncertainty, conflict between the constraint of sustainability and social and economic priorities, poorly defined objectives, and institutional failures related to access rights and participation in management by the users. These issues point to the real complexity of fisheries management. It is argued that this complexity can be abused by all interest groups to avoid responsibility and to suit their own objectives. It is suggested that there are eight simple principles controlling fisheries management that are generally well‐understood and, if properly considered in fisheries management systems, would lead to improved performances. Responsible management will, however, only be effective if there is a genuine desire to achieve the objectives. Fishing capacity, frequently reflecting dependency of users on fisheries resources, is commonly in excess of the sustainable production of the resources. Excess dependency can preclude the political will to consider alternative strategies and only once it has been overcome, probably requiring solutions borrowed from outside fisheries, is effective management likely to be considered seriously. Thereafter, responsible management requires setting unambiguous objectives and management measures in co‐operation with users and other interest groups. The agreed strategy must be included in legislation to ensure transparency and accountability and to constrain decision‐makers. The performance of the strategy must be monitored and revised as necessary.     

Will philopatry in sea bass, Dicentrarchus labrax, facilitate the use of catch-restricted areas for management of recreational fisheries?

Many adult sea bass (>40 cm total length) tagged between May and October around the coasts of England and Wales have been recaptured close to their respective tagging locations in successive years. Analysis of mark and recapture data sets, for the late 1970s and early 1980s and in 2000–2006, show that some 55% of all recaptures were within 16 km of their original release position. This suggests that mortality rates of adult bass in local populations could be reduced by around 50% if a number of carefully selected areas were designated as catch and release only for bass, thus providing a management option with which more and bigger sea bass will be available to recreational sea anglers.     

The cooperation between the Chinese Bureau of Fisheries and the Norwegian Directorate of fisheries

Activities1994In 1994 Peter Gullestad(Present Director General of Fisheries in Bergen) headed a Norwegian delegationvisiting China.In his presentation of“The N orwegian exp erience in fisheries management and control” - hestressed the fact that overcapacity is“the root of all evil”.He also underlined that it is important not only toset up a legal system for fisheries management but also to establish reliable catch statistics.He further morepointed out that good scientific advice is th…     

Decline and fall of the salmon fisheries in the Netherlands: is restocking the Rhine a reality?

Abstract. The Atlantic salmon, Salmo salar L., was once of major importance to the fishing industry along the River Rhine. This paper discusses the Dutch and German salmon catches over the years 1863–1950. Even up to the end of the last century, it was not uncommon for Dutch and German fishermen to land 100000 salmon a year. However, factors such as the increased use of locks and weirs along the Rhine, coupled with growth in pollution, soon led to a rapid decline in numbers. By 1933, the salmon fishing industry in the Netherlands had virtually ceased to exist. Analysis of the available catch statistics suggests that the decline in the salmon population could have started before official records began. Although the degree of scatter in the data and uncertainties in the assumptions preclude the possibility of drawing firm conclusions about the survival rate of salmon, these figures illustrate how difficult it will be to maintain a stable population in the Rhine. Moreover, a number of changes have taken place since the heyday of salmon in western Europe, which could compound the problem. Of particular importance in the context of the Rhine are:

• 1 the closure of two of the major migration routes to the sea (Haringvliet and Zuiderzee);
• 2 morphological changes in the river;
• 3 chemical and thermal pollution;
• 4 the loss of accessible spawning and nursery areas of the required quality;
• 5 the disappearance of salmon from other rivers that flow into the North Sea such as the Rivers Elbe, Weser and Ems. If salmon were only reintroduced into the Rhine, a certain proportion would probably stray and infiltrate these other rivers.

The fact that the impact of these changes is difficult to quantify increases the uncertainty associated with maintaining a stable stock of salmon in the Rhine.     

Impact of the 2014–2016 marine heatwave on US and Canada West Coast fisheries: Surprises and lessons from key case studies

Marine heatwaves are increasingly affecting marine ecosystems, with cascading impacts on coastal economies, communities, and food systems. Studies of heatwaves provide crucial insights into potential ecosystem shifts under future climate change and put fisheries social-ecological systems through “stress tests” that expose both vulnerabilities and resilience. The 2014–16 Northeast Pacific heatwave was the strongest and longest marine heatwave on record and resulted in profound ecological changes that impacted fisheries, fisheries management, and human livelihoods. Here, we synthesize the impacts of the 2014–2016 marine heatwave on US and Canada West Coast fisheries and extract key lessons for preparing global fisheries science, management, and industries for the future. We set the stage with a brief review of the impacts of the heatwave on marine ecosystems and the first systematic analysis of the economic impacts of these changes on commercial and recreational fisheries. We then examine ten key case studies that provide instructive examples of the complex and surprising challenges that heatwaves pose to fisheries social-ecological systems. These reveal important insights into improving the resilience of monitoring and management and increasing adaptive capacity to future stressors. Key recommendations include: (1) expanding monitoring to enhance mechanistic understanding, provide early warning signals, and improve predictions of impacts; (2) increasing the flexibility, adaptiveness, and inclusiveness of management where possible; (3) using simulation testing to help guide management decisions; and (4) enhancing the adaptive capacity of fishing communities by promoting engagement, flexibility, experimentation, and failsafes. These advancements are important as global fisheries prepare for a changing ocean.     

Does propeller turbulence affect the sink rate of baited hooks and their availability to seabirds in pelagic longline fisheries?

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Profiles of sex steroids, fecundity and spawning of a migratory characiform fish from the Paraguay–Paraná basin: a comparative study in a three-river system

This study investigated for the first time the reproductive biology of Prochilodus lineatus in a system of rivers in southeastern Brasil, relating it to the role of tributary rivers in the reproductive success of this important commercial fish in the Upper Paraná River basin, where a cascade of hydroelectric dams were deployed. Specimens were caught bimonthly in three river sites: (S1) Grande River, downstream from the Porto Colômbia dam; (S2) Pardo River; and (S3) Mogi Guaçu River. Sex steroid plasma levels, fecundity, follicular atresia, oocyte diameter and gonadosomatic index (GSI) were compared among sites. In S1, fish exhibited changes in the reproductive parameters: lower GSI, oocyte diameter and fecundity and higher follicular atresia index, when compared to S2 and S3. Frequency of maturing fish was higher in S3 and spawning was only registered in S3. In sites S2 and S3, plasma concentrations of testosterone and 17β-estradiol in females and testosterone in males showed wide variations following gonadal maturation. Fish from S1 showed few significant variations in sex steroid concentrations throughout the gonadal cycle. These results indicate that P. lineatus does not reproduce in Grande River (S1), but probably uses the Pardo River (S2) as a migratory route towards the Mogi Guaçu River (S3) where they complete gonadal maturation and spawning. Our findings contribute for understanding the reproductive biology of P. lineatus and to highlight the importance of tributaries in impounded rivers as a favourable environment for migration and spawning of fish.     

Breeding,economic traits evaluation,and commercial cultivation of a new Saccharina variety “Huangguan No. 1”

New variety breeding is very significant for Saccharina japonica cultivation industry. In this paper, we reported the breeding process, evaluation of economic traits, and commercial cultivation of a new Saccharina variety “Huangguan No. 1” (variety approval number: GS-01-006-2011). The sporophytes with best performance were screened out from varieties cultivated throughout Fujian Province, China, and mixed together as the parent population. The “Huangguan No. 1” variety was bred successfully from 5 years of targeted selection of objective traits and continuous progeny selfing/inbreeding. This new variety has a much longer, wider, and thicker blade; faster growth rate; heavier individual weight; and stronger resistance to high temperatures compared to the control variety (p < 0.05). Cultivation tests showed that the economically important traits remained steady in different years and sea areas, implying that “Huangguan No. 1” has the stable genetic basis for its excellent performance. Compared to the control variety, the yield and final product rate of “Huangguan No. 1” increased 30 and 25 %, respectively. Nutritional constituent analysis indicated that “Huangguan No. 1” could be used as a healthy food because of its higher protein (6.85 %) but lower fat content (0.2 %). Heavy metal (As, Cd, Pb) content was lower than the standard content for food safety. The suitability of “Huangguan No. 1” as a food source rather than a raw material for the chemical industry was increased due to the low algin (10.2 %) and iodine content (0.32 %). “Huangguan No. 1” variety was welcomed by farmers and has been commercially cultivated about 13,293 ha.     

Raphidascaris acus (Bloch, 1779) larvae infections of the stone loach, Barbatula barbatula (L.), from the River Haná, Czech Republic

The stone loach, Barbatula barbatula (L.), is a typical and dominant intermediate host of Raphidascaris acus in lowland streams of Central Europe. The prevalence of infection of R. acus in B. barbatula from the River Haná ranged throughout the year from 73.3 to 100%. The abundance and the mean intensity of infection also varied throughout the year with a peak in September. Larvae were located mainly in the liver parenchyma. High numbers of larvae and their migration through the tissue caused cyst- or abscess-like formations in the host parenchyma. The severity of the disease condition ranged from mild to severe. We speculate that the infection of stone loach by R. acus larvae regulates the population density and abundance of the intermediate host in lowland streams where natural predators are absent.     

Studies on activity, distribution, and zymogram of protease, α-amylase, and lipase in the paddlefish Polyodon spathula

A series of biochemical determination and electrophoretic observations have been conducted to analyze the activities and characteristics of protease, α-amylase, and lipase of paddlefish Polyodon spathula. The results obtained have been compared with those of bighead carp (Aristichthys nobilis) and hybrid sturgeon (Huso dauricus ♀?×?Acipenser schrenki Brandt ♂), in order to increase available knowledge of the physiological characteristics of this sturgeon species and to gain information with regard to its nutrition. Further, a comparative study of enzymatic activity, distribution, and characterization between commercial feed-reared paddlefish (CG) and natural live food-reared (NG) paddlefish was conducted. Results showed that higher proteolytic activity was observed in the pH range 2.5-3.0 and at a pH of 7.0 for paddlefish. Levels of acid protease activity of paddlefish were similar to that of hybrid sturgeon, and significantly higher than that of bighead carp. The inhibition assay of paddlefish showed that the rate of inhibition of tosyl-phenylalanine chloromethyl ketone was approximately 2.6-fold that of tosyl-lysine chloromethyl ketone. There was no significant difference observed for acid protease activity between PG and CG groups, whereas the activity of alkaline protease, α-amylase, and lipase in the PG group were significantly lower than those in the CG group. The substrate sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis further showed that there were certain types of enzymes, especially α-amylase, with similar molecular mass in the paddlefish and hybrid sturgeon. It can be inferred that acid digestion was main mechanism for protein hydrolysis in paddlefish, as reported for other fishes with a stomach. This indicates that the paddlefish requires higher alkaline protease, α-amylase, and lipase activity to digest natural live food.     

On sightings of (vagrant?) monk seals,Monachus monachus,in the Mediterranean Basin and their importance for the conservation of the species

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Habitat and prey selection of common minke,sei, and Bryde’s whales in mesoscale during summer in the subarctic and transition regions of the western North Pacific

This study represents the first quantitative analysis of the characteristics of the distribution areas and stomach contents of common minke whale Balaenoptera acutorostrata, sei whale B. borealis, and Bryde’s whale B. edeni in relation to oceanographic and prey environments in mid summer in the western North Pacific. Common minke whales were distributed within subarctic regions and the northernmost region of the transitional domain, coinciding with the main habitat of their preferred prey, Pacific saury Cololabis saira. Sei whales were mainly found in the northernmost part of the transition zone and showed prey preference for Japanese anchovy Engraulis japonica, which was significantly more abundant in the main distribution area of the whale than in its adjacent areas. “Hot spots” of Bryde’s whales were found in several regions of the transition zone between the subarctic boundary and the Kuroshio front. This whale species preferred Japanese anchovy as prey, for which the distribution density was significantly higher in the main distribution area of the whale than in the adjacent areas. These results indicate that the summer distributions of Pacific saury and Japanese anchovy greatly influence the distributions of these whale species, suggesting that the whales’ habitat selection is closely related to their prey selection.     

Influence of food type,amount, and frequencies on the larviculture of pacamã catfish Lophiosilurus alexandri

This study assessed the performance of L. alexandri postlarvae (2 days after hatching) with different diets (Artemia and Panagrellus redivivus), food amounts (C₃₀₀-C₅₀₀-C₇₀₀), and feeding frequencies (F₁-F₃-F₆) in two experiments lasting 10 days. The best performing food type, Artemia and Artemia with P. redivivus, presented the highest survival rates as well as fish with the greatest weight, length, and specific growth rate (SGR). In the second experiment with Artemia, the weight, length, and SGR presented significant differences, increasing with higher amounts of prey. The best performance was obtained from a daily diet (F₁) with the greatest amount of prey (C₇₀₀).     

Sustainability of fishers’ communities in tropical island fisheries from the perspectives of resource use and management: a comparative study of Pohnpei (Micronesia), Mafia (Tanzania), and Guimaras (Philippines)

The fisheries structure, fishing gear, fishing vessels and their ownership, landing sites and markets, as well as fisheries management and fishers’ participation were surveyed in three tropical islands: Pohnpei (Micronesia), Mafia (Tanzania), and Guimaras (Philippines), covering 127 fishers. Labour-intensive gear, including purse seines and ring nets, characterised Mafia fisheries. Fibre-reinforced plastic (FRP) boats characterised Pohnpei fisheries, and canoes with nonmarine engines were characteristic of Guimaras fisheries. Wooden plank boats with large crews were only seen in Mafia. From a gear/vessel ownership perspective, the fisher categories present were gear fishers, gear-vessel fishers, employers, and casual labour fishers. Casual labour fishers and employers were only apparent in Mafia. The fisheries in Pohnpei had a relatively early age of entry, which was attributed to the urban markets available and family cohesion, while community organisation-based management of these fisheries was weak. Mafia and rural Guimaras fishers depended on middlemen, due to the distance of the market. Deteriorating subsistence-related fishery dependency means that the Guimaras fishers’ community is at risk. The high shared gear/vessel ownership rates and levels of affiliation to community organisations in Mafia reflect government’s timely community sustainability enhancement initiative. Based on our analyses, we propose the “fishers’ community sustainability” concept. The sustainability of a fisher’s community can be judged on (1) the age of entry to the fisheries, (2) the monetary profits made at fish markets and through marketing, (3) the cohesion among the fishers, and (4) the level of subsistence-related dependency on the fishery. The fishery is key to community sustainability, thus ensuring fishery-dependent life. It is essential to consider the above indicators of fishers’ community sustainability during fisheries development.     

Wealth and welfare? Can fisheries management succeed in achieving multiple objectives? A case study of Lake Victoria,East Africa

Fisheries policies often pursue multiple objectives, which may, in some instances, be in conflict or competition with each other. It may not be possible, for example, to create or maintain employment and generate increasing volumes of revenue for government whilst also sustaining stocks and biodiversity. Two approaches to fisheries management, one focused on capturing wealth and limiting access and the other on maintaining access for employment and providing community development and welfare, present contrasting policy advice, with different points of emphases and objectives. This article examines the case of Lake Victoria, where the three main commercial fisheries are seen to contribute to different objectives for the lake's fisheries. Insights from the debate between wealth‐based and welfare‐based approaches to fisheries management provide a framework for the analysis of fisheries policy and practice on the lake. From the analysis, it is concluded that whilst there is much rhetoric in support of a wealth‐based approach, this has not been followed through in implementation, reflecting the lack of political support for new taxation and limiting access. The welfare functions of the fisheries are significant, but could be substantially strengthened through greater investment in the provision of services to fisheries communities. The approaches are not mutually exclusive, but pursuing wealth‐based management must support livelihoods, employment and development, as well as fisheries management objectives. Without the incorporation of welfare objectives, fisheries policies will not be politically accepted or fully implemented, suggesting the need for a balance between wealth and welfare objectives and measures.     

Comparison of 3,5,3′-triiodo-L-thyronine and L-thyroxine absorption from the intestinal lumen of the fasted rainbow trout,Oncorhynchus mykiss

The absorptions of 3,5,3-triiodo-L-thyronine (T₃) and L-thyroxine (T₄) from the intestinal lumen of the rainbow trout were compared in vivo. Tracer doses of [¹²⁵I]T₄ (⁺T₄) or [¹²⁵I]T₃ (^*T₃) were injected through an anal cannula into the duodenum of trout fasted for 3 days at 12°C, and radioactivity was measured in blood and tissues at 4–48 h. ^*T₃ was removed more extensively than ^*T₄ from the intestinal lumen and more radioactivity was absorbed into the blood and tissues of u+T₃-injected trout than ^*T₄-injected trout. HPLC analysis showed that a high proportion of the radioactivity in the plasma, liver, kidney and intestinal lumen of ^*T₃-injected trout remained as the parent ^*T₃. However, in ^*T₄-injected trout most plasma radioactivity was in the form of ¹²⁵I^–, and by 24 h a high proportion of luminal radioactivity was ¹²⁵I^–. By 48 h, over 4% of the injected ^*T₃ and 1% of the injected ^*T₄ dose resided in the gall bladder, primarily as derivatives of ^*T₃ or ^*T₄. We conclude that T₃ is absorbed more effectively than T₄ from the intestinal lumen of fasted trout, indicating the potential for an enterohepatic T₃ cycle.     

The Effect of Frying – the Chemical,Microbiological, and Acrylamide Composition of Mussels as a Street Food

The effects of frying methods and covering processes on the proximate composition, fatty acid profile, amino acid profile, cholesterol, acrylamide, and microbiological content of fried mussel (Mytilus galloprovincialis 1819) were investigated in the present study. The group of mussels that were purchased for study was divided into six groups (control – unprocessed mussel meat; Group A – covered mussels fried in deep fat; Group B – mussel fried in low fat; Group C – uncoated mussel meat fried in deep fat; Group D – uncoated mussel fried in low fat; and Group E – mussel served in restaurants). It was determined that the mussel frying methods can affect the nutritional composition and cause changes in the amino acid, fatty acid, and cholesterol content.     

Bioaccumulation of hexachlorocyclohexane,dichlorodiphenyltrichloroethane, and estradiol-17β in catfish and carp during the pre-monsoon season in India

This investigation was performed to monitor hexachlorocyclohexane isomers (HCHs), dichlorodiphenyltrichloroethane (DDT, and its metabolites, refered to as DDTs), plasma levels of estradiol-17β (E2), and the gonadosomatic index (GSI) between sampling sites of unpolluted ponds of Gujartal, Jaunpur (control site) and the polluted rivers Gomti (Jaunpur) and Ganga (Varanasi), which affect the reproductive physiology of some edible catfish and carp during the pre-monsoon season. HCHs and DDTs were measured by gas liquid chromatography (GLC) and hormones by radioimmunoassay (RIA). The results indicated that the level of HCHs and DDTs was very high in both the catfish and the carp captured from the polluted rivers compared with the fish captured from the control site. The GSI and E2 values were lower in both groups of fish when compared to the fish from the control site. The results also indicate that catfish showed greater bioaccumulation of HCHs and DDTs than carp, above the permissible limit, as compared to the fish from the control site. In conclusion, fish from the Gomti and Ganga rivers were highly polluted when compared with fish from the control site, as was evident from high levels of tissue bioaccumulation of HCHs and DDTs and decreased levels of plasma E2, inhibiting the reproductive physiology of these species at the receptor level. The levels exceeded the maximum residue limits (MRL) as recommended by Codex, hence it is suggested that the fish should be avoided for food purposes.     

Molecular cloning of the cDNA encoding the β subunit of thyrotropin and regulation of its gene expression by thyroid hormones in the goldfish, Carassius auratus

A cDNA encoding the subunit of thyrotropin (TSH) was isolated from a goldfish (Carassius auratus) pituitary gland cDNA library. By comparing the sequence with other teleost TSHs, a signal peptide of 19 amino acids and a mature hormone of 131 amino acids were predicted for goldfish TSH subunits. The resulting putative mature hormone of 131 amino acids had well-conserved cysteine positions and a putative N-linked glycosylation site; homology was 51–67% with TSHs from other teleosts, 38–43% with tetrapod TSHs, but only 27 and 29% with goldfish GTH-I and -II, respectively. We also examined the effects of thyroid hormones (TH) and thiourea (TU, an inhibitor of TH production) treatments on TSH and GTH subunit gene expressions in the goldfish pituitary gland. After thyroxine (T₄) treatment, circulating T₄ concentration increased and TSH mRNA level decreased. Supressing the amount of circulating T₄ and triiodothyronine (T₃) by TU treatment increased the TSH mRNA level. Moreover, T₄ replacement therapy (simultaneous treatment of both TU and T₄) caused a high level of circulating T₄ and a low level of circulating T₃, and a decrease in the TSH mRNA level. Thus, changing levels of circulating TH exert a negative feedback on the level of TSH subunit mRNA in goldfish in vivo. On the other hand, GTH subunit mRNA levels were not affected by changes in the levels of circulating TH.