Dwindling food-fish species and fishers' preference: problems of conserving Lake Malawi's biodiversity

Most of Malawi's popular food-fish species are in decline. The fishers attribute this decline to overfishing, changes in climate, inadequate fishing technology and supernatural powers. Sedimentation of the lake and rivers due to poor agricultural practices, which can also be implicated in the demise of Malawi's fisheries, was not recognized by the fishers. This study tested and confirmed that the fishers would readily switch to exploiting ornamental fish (Mbuna) for subsistence and cash if the more favoured food-fish species continued to dwindle. However, as most of the Mbuna species are localized to specific rocky habitats and are endemic to certain parts of the lake, they may be vulnerable to overfishing. To safeguard Lake Malawi's rich fish species diversity: (i) alternative economic opportunities for the lakeshore people should be identified, evaluated and promoted to alleviate the fishing pressure, (ii) the Department of Fisheries should collaborate with local fishermen in promoting sustainable fish utilization, e.g., through public campaigns aimed at sensitizing fishermen on the status of the fisheries and the vulnerability of some fish communities to overfishing and environmental degradation, and (iii) the degree of Mbuna exploitation, now that the popular food fishes are in decline, should be monitored and, where necessary, regulated to promote sustainability.     

From Ethnobiology to Ecotoxicology: Fishers’ Knowledge on Trophic Levels as Indicator of Bioaccumulation in Tropical Marine and Freshwater Fishes

Information on fish trophic levels is important to assess fishing impacts and to better understand the bioaccumulation of pollutants within aquatic food chains. The local ecological knowledge held by small-scale fishers can fill knowledge gaps in fish trophic ecology. We estimated the trophic levels of 69 tropical and subtropical fish species (33 coastal and 36 freshwater species) using data on fish diets from the literature and obtained from interviews with Brazilian fishers. The fish trophic levels estimated from fishers’ knowledge were positively correlated with the trophic levels estimated using data from biological studies for both coastal and freshwater fish. The fishers’ knowledge also indicated bioaccumulation patterns, as the fish trophic levels estimated from fishers’ knowledge were positively related to the mercury (Hg) content in fish muscle (wet weight, from literature data) in 41 fish species (15 coastal and 26 freshwater). These findings reveal the potential for new applications of fishers’ knowledge to ecotoxicology, which could improve management of aquatic ecosystems and strengthen fishers’ political status.     

Costly signaling and torch fishing on Ifaluk atoll

In this paper I evaluate the merit of costly signaling theory (CST) as a paradigm for understanding why men of Ifaluk atoll torch fish. I argue that torch fishing is a handicap that signals men's productivity. Consistent with CST, torch fishing is observed by the predicted audience (women), energetically costly to perform, and a reliable indicator of the frequency a man fishes during the trade wind season. Contrary to expectations of who should benefit from torch fishing and consequently participate, torch fishers are not primarily young and unmarried. Torch fishers, however, are predominately from the matriline that owns the canoe on which they fish, suggesting that torch fishing also signals the productivity of a matriline. Although these results support the possibility that torch fishing is a handicap, no data are presented which demonstrate that torch fishers achieve any gains from sending the costly signal. This shortcoming and other directions for future research on Ifaluk foraging decisions are discussed.     

Spatio-Temporal Dynamics of Exploited Groundfish Species Assemblages Faced to Environmental and Fishing Forcings: Insights from the Mauritanian Exclusive Economic Zone

Environmental changes and human activities can have strong impacts on biodiversity and ecosystem functioning. This study investigates how, from a quantitative point of view, simultaneously both environmental and anthropogenic factors affect species composition and abundance of exploited groundfish assemblages (i.e. target and non-target species) at large spatio-temporal scales. We aim to investigate (1) the spatial and annual stability of groundfish assemblages, (2) relationships between these assemblages and structuring factors in order to better explain the dynamic of the assemblages’ structure. The Mauritanian Exclusive Economic Zone (MEEZ) is of particular interest as it embeds a productive ecosystem due to upwelling, producing abundant and diverse resources which constitute an attractive socio-economic development. We applied the multi-variate and multi-table STATICO method on a data set consisting of 854 hauls collected during 14-years (1997–2010) from scientific trawl surveys (species abundance), logbooks of industrial fishery (fishing effort), sea surface temperature and chlorophyll a concentration as environmental variables. Our results showed that abiotic factors drove four main persistent fish assemblages. Overall, chlorophyll a concentration and sea surface temperature mainly influenced the structure of assemblages of coastal soft bottoms and those of the offshore near rocky bottoms where upwellings held. While highest levels of fishing effort were located in the northern permanent upwelling zone, effects of this variable on species composition and abundances of assemblages were relatively low, even if not negligible in some years and areas. The temporal trajectories between environmental and fishing conditions and assemblages did not match for all the entire time series analyzed in the MEEZ, but interestingly for some specific years and areas. The quantitative approach used in this work may provide to stakeholders, scientists and fishers a useful assessment for the spatio-temporal dynamics of exploited assemblages under stable or changing conditions in fishing and environment.     

Marine Invertebrate Conservation: Evaluation of Fisheries Over-exploitation Concerns

The nature of overfishing of marine invertebrates is complex,ranging from the perception of overfishing because of competitionby user groups for a common property resource to extensive overfishingto near extinction because of poaching by either licensed orunlicensed fishers. As a group, marine invertebrates seem particularlyresistant to overfishing, primarily because their relative immobilityand scattered concentrations means refuge populations oftenexist. However, this distribution pattern also means a fisheryis scattered over an often large geographical area with relativelysmall, frequent landings at any location. A minimum legal sizeregulation, enforceable anywhere before consumption, is theprimary regulation applied by managers for many species to ensureagainst overfishing. Overfishing concerns arise primarily forthose species where price is sufficiently high to encourageillegal fishing or where harvest by fishers is not easily monitoredor controlled because of the nature of the fishing activityor because only part of the animal (e.g., the flesh) is harvested.Instances of overfishing by cause are discussed, and examplesare presented to demonstrate how managers are dealing with orhave dealt with different situations.     

Environmental variability and the fishery dynamics of the Okavango delta, Botswana: the case of subsistence fishing

The hydrological regime of the Okavango River Basin is the main driver of ecological change in the delta. The delta supports a small-scale fishery which is a source of livelihood for communities within its fringes. The fish resource is particularly important to subsistence fishers, who have limited access to socio-economic opportunities. However, fish availability is subject to 'concentration and dilution' effects because of the hydrological regime. As a copying strategy, fishers use a variety of fishing methods to effectively harvest the delta's fish community across all its trophic levels. This exploitation regime helps to maintain the delta's species diversity and only reduces fish biomass proportionally across the different trophical levels. Furthermore, fishers have developed different fish-processing techniques to preserve their harvest for low fishing season periods to cope with low food availability. The aim of this paper therefore, was to explore spatio-temporal variations in fish availability and to show how the delta's subsistence fishers cope with this dynamicity.     

Gear selectivity of functional traits in coral reef fisheries in Brazil

Small-scale reef fisheries are important commercial and subsistence activities that support the livelihoods of millions of people in tropical regions. Tropical marine fisheries typically target a diversity of species caught with a matching diversity of fishing gears and practices. Here, we explored how multiple fishing gears select for distinct functional traits of fish assemblages inside a large multiple use marine environmental protected area off northeastern Brazil. In 1833 landing interviews with local fishers, we identified 101 species, which were categorized according to six traits: body size, schooling behavior, mobility, position in the water column, diet and period of activity. Our research is the first to explore the broad patterns of gear selectivity with regards to fish functional traits for different habitat types. While gears used in reef habitats were highly selective of sedentary and benthic species that form schools with few individuals, gears used in coastal lagoons were selective of highly mobile pelagic species that form large schools. We found a low competitive interaction between different gear types, meaning there was a low overlap in trait selectivity between fishing gears. We also found direct associations between gears and fish functional traits: hooks and line targeted species that exhibit limited mobility capabilities, making these species more vulnerable to local levels of fishing effort. In contrast, nets and fish corrals targeted mobile species that exhibited a greater diversity of functional traits. Some of our results contrasted with the current literature on the topic, with differences highlighting the need for more research to clarify global patterns of trait selectivity by gear type. Our results have implications for fisheries management in northeastern Brazil: gear bans and effort caps are commonly used management measures that can foster fisheries sustainability by minimizing impacts to fish assemblage functions.

     

Movements of undersized spotted grunter (<Emphasis Type="Italic">Pomadasys commersonnii</Emphasis>) in the Great Fish Estuary,South Africa: implications for fisheries management

The purpose of this study was to test the hypothesis that an estuarine species as the spotted grunter Pomadasys commersonnii is evenly distributed within the estuary and uniformly exploited by different groups of fishers. This was done by investigating the movements and area use of spotted grunter in relation to the fisheries. The position of 20 acoustically tagged fish was recorded during 36 days in February and March 2003, by manual tracking and automated data logging receivers. Information on the fisheries in the estuary was collected through visual registration of fishing effort and interviews. The spotted grunter moved on average 1.0 km (SD ± 0.7) between positional fixes. Most of the fish were positioned in the lower part of the 12 km long estuary, as 70% of the positional fixes were within the first 3 km, and 89% within the first 6 km. Approximately half (49%) of all the fixes were between 1.0 and 1.5 km from the estuary mouth. The spotted grunter used on average 4.9 km (SD ± 4.9) of the length of the estuary, and there was no significant relationship between the length of the estuary used and the body length of the fish (26–39 cm TL). Subsistence fishers accounted for 73% of fishing lines in the water, while recreational fishers accounted for the rest. Ninety-three percent of the lines were recorded within the first 6 km from the estuary mouth, of which 80% were recorded within the first 3 km. Almost 1/3 of the fishing effort was recorded between 1.0 and 1.5 km from the mouth. The hypothesis that the estuarine dependent species spotted grunter was evenly distributed within the estuary was rejected. However, there was a significant relationship between the distribution of the fishing effort of the subsistence fishers and the fish, indicating that the spotted grunter was uniformly exploited within the estuary by this group of fishers. In contrast, there was no relationship between the distribution of fish and recreational anglers.     

Using an Ecosystem Modeling Approach to Explore Possible Ecosystem Impacts of Fishing in the Beibu Gulf,Northern South China Sea

Using the Ecopath with Ecosim software, a trophic structure model of the Beibu Gulf was constructed to explore the energy flows and provide a snapshot of the ecosystem operations. Input data were mainly from the trawl survey data collected from October 1998 to September 1999 and related literatures. The impacts of various fishing pressure on the biomass were examined by simulation at different fishing mortality rates. The model consists of 20 functional groups (boxes), each representing organisms with a similar role in the food web, and only covers the major trophic flows in the Beibu Gulf ecosystem. It was found that the food web of the Beibu Gulf was dominated by the primary producers path, and phytoplankton was the primary producer mostly used as a food source. The fractional trophic levels ranged from 1.0 to 4.02, and the marine mammals occupied the highest trophic level. Using network analysis, the ecosystem network was mapped into a linear food chain, and six discrete trophic levels were found with a mean transfer efficiency of 11.2%. The Finn cycling index was 9.73%. The path length was 1.821. The omnivory index was 0.197. The ecosystem had some degree of instability due to exploitation and other human activities, according to Odum’s theory of ecosystem development. A 10-year simulation was performed for each fishery scenario. The fishing mortality rate was found to have a strong impact on the biomass. By keeping the fishing mortality rate at the current level for all fishing sectors, scenario 1 had a drastic decrease in the large fish groups. The biomass of the small and medium pelagic fish would increase to some extent. The biomass of the small and low trophic level species, jellyfish, prawns and benthic crustaceans would be stable. The total biomass of the fishery resources would have a 10% decrease from the current biomass after 10 years. In contrast, the reduced fishing mortality rate induced the recovery of biomass (scenarios 2–4). In scenario 2, the biomass of the large demersal fish and the large pelagic fish would increase to over 16 times and 10 times, respectively, of their current level. In scenario 4, the biomass of the large pelagic fish would increase to over 3 times of its current level. The total biomass of the fish groups, especially the high trophic level groups, would become significantly higher after 10 years, which illustrates the contribution on biomass recovery by relaxing the fishing pressure. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Author contributions: Xiaoping Jia designed research; Zuozhi Chen and Yongsong Qiu performed research; Zuozhi Chen, Yongsong Qiu, and Shannan Xu analyzed data; and Zuozhi Chen and Shannan Xu wrote the article.     

Co-management and Spatial Features Contribute to Secure Fish Abundance and Fishing Yields in Tropical Floodplain Lakes

Empirical data are needed to show the efficacy of co-management, which is regarded as a promising approach to achieve conservation goals. In this study, we addressed the potential influence of fisheries co-management to increase fish abundance and fishing yields in the lower Tocantins River Basin (Brazilian Amazon), downstream from a large dam. We analyzed 590 fish landings (6.7 t of fish) from five fishing villages and 48 fish samples obtained using gillnets (10,378 fish from 101 species) in 12 floodplain lakes in four regions: two with incipient co-management and two unmanaged. The fish species richness did not differ among the regions, but the lakes in the regions that were co-managed had higher fish abundance (biomass and number of individuals) and a higher mean proportion of fish reproducing during the high water season. Fishers had higher catches per unit of effort in the co-managed regions than fishers in the non-managed regions. These results were also influenced by geographic factors (distance and accessibility of lakes), as fish biomass was higher in lakes that were distant from the main river and from the main city in the region. Managers should thus consider strategic selection of the geographic locations of managed sites, even in remote areas. However, the fish biomass sampled in lakes was more related to region than to the lakes’ geographical location. Therefore, co-management has at least partially contributed to increased fish abundance and fishing yields in the studied region, through the protection of an important fish habitat (lakes). We provide empirical evidence that co-management can contribute to the maintenance of fish abundance, sustainability of fisheries, and food security in large tropical rivers impacted by damming.     

Effects of fishing on parasitism in a sparid fish: contrasts between two areas of the Western Mediterranean

This study addressed the impacts of fishing on the rates of parasitism using the sparid Boops boops as a model fish species. Using a large suite of parasite species in B. boops, with different life histories, transmission pathways and host specificity, we compared parasite diversity, prevalence, abundance and community structure at two Mediterranean localities in the Balearic Sea, Santa Pola Bay and the Gulf of Oran, that are characterised by a contrasting pattern of fishing of B. boops. A total of 360 fish were examined comprising nine distinct samples collected during the warm and the cold weather months. A total of 29 parasite species were identified, with eight species in common for the two localities. Parasite component communities at Santa Pola Bay were more species rich and abundant than those at the Gulf of Oran and exhibited a different community structure. Of the eight common taxa used in the quantitative comparisons, five exhibited significant difference for prevalence between the two localities, four having substantially higher prevalence at Santa Pola and only one being more prevalent at the Gulf of Oran. Two specialist trematodes and the sparid generalist monogenean exhibited consistently higher prevalence and abundance at Santa Pola Bay than at the Gulf of Oran; the two specialists were also identified as key species for assigning individual fish to their locality of origin. The consistent differences in the richness, abundance and structure of parasite communities in B. boops from Santa Pola Bay and the Gulf of Oran may reflect the contrasting patterns of exploitation of the populations of this fish host at the two localities.     

The small-scale urban reservoir fisheries of Lago Paranoá, Brasília, DF, Brazil.

In many cases in large urban centers, which have appropriate waterbodies, small-scale fisheries are the only source of cheap protein for the poor. In Lago Paranoá, located in Brasília, the capital city of Brazil, fishing was studied by conducting interviews with 53 fishers filling in logbooks from March, 1999 to March, 2000 in three fishing communities. The fishers come from the poorest towns around Brasília, known as satellite-towns. They have been living there on average for 21.7 years (s = 9.6 years), their families have 4.9 members (s = 3.6) on average and 44.2% do not have a basic education. However, such characteristics are similar to the socioeconomic indices of the metropolis where they live. In spite of being illegal between 1966 and 2000, fishing generated an average monthly income of U 239.00 dollars (s = U 171.77 dollars). The Nile Tilapia Oreocrhromis niloticus is the main captured species (85% of a total number of landings in weight of 62.5 t.). Fishing is carried out in rowing boats, individually or in pairs. The fishing equipment used are gillnets and castnets. Gillnets were used actively, whereby the surface of the water is beaten with a stick to drive Tilapias towards nets as they have the ability to swim backwards. This fishing strategy was used in 64.7% of the fisheries, followed by castnets (31.1%) and by gillnets which were used less (4.2%). The fish is sold directly in the streets and fairs of the satellite-towns to middlemen or to bar owners. Three communities have different strategies in terms of fishing equipments, fishing spots and commercialization. Consequently, there are statistically significant differences in relation to the monthly income for each one of these communities.     

A Mixed-Method Approach for Quantifying Illegal Fishing and Its Impact on an Endangered Fish Species

Illegal harvest is recognized as a widespread problem in natural resource management. The use of multiple methods for quantifying illegal harvest has been widely recommended yet infrequently applied. We used a mixed-method approach to evaluate the extent, character, and motivations of illegal gillnet fishing in Lake Hovsgol National Park, Mongolia and its impact on the lake’s fish populations, especially that of the endangered endemic Hovsgol grayling (Thymallus nigrescens). Surveys for derelict fishing gear indicate that gillnet fishing is widespread and increasing and that fishers generally use 3–4 cm mesh gillnet. Interviews with resident herders and park rangers suggest that many residents fish for subsistence during the spring grayling spawning migration and that some residents fish commercially year-round. Interviewed herders and rangers generally agree that fish population sizes are decreasing but are divided on the causes and solutions. Biological monitoring indicates that the gillnet mesh sizes used by fishers efficiently target Hovsgol grayling. Of the five species sampled in the monitoring program, only burbot (Lota lota) showed a significant decrease in population abundance from 2009–2013. However, grayling, burbot, and roach (Rutilus rutilus) all showed significant declines in average body size, suggesting a negative fishing impact. Data-poor stock assessment methods suggest that the fishing effort equivalent to each resident family fishing 50-m of gillnet 11–15 nights per year would be sufficient to overexploit the grayling population. Results from the derelict fishing gear survey and interviews suggest that this level of effort is not implausible. Overall, we demonstrate the ability for a mixed-method approach to effectively describe an illegal fishery and suggest that these methods be used to assess illegal fishing and its impacts in other protected areas.     

Community Based Fisheries Management and Fisher Livelihoods: Bangladesh Case Studies

Poor fishers in Bangladesh have been disadvantaged by policies that favored powerful people leasing fishing rights. Community-based management was expected to improve fisher access, livelihoods, and the sustainability of fisheries. The impacts of community management in three floodplain waterbodies differed according to the environment and property rights. Where a set of fishers jointly held exclusive rights to a small enclosed lake they increased production by stocking fish and shared the returns. This strategy is productive but attracts competition for profits and fish consumption was unchanged. Access to capture fisheries in floodplain waterbodies enables the poor to catch diverse small fish for their consumption. Yet sustainability requires limits on fishing. Fish sanctuaries were respected, yet catches per day fell when more people from several villages increased fishing effort in a large wetland, while a tightly knit community restored the fishery in a smaller floodplain. Community organizations will need recognition of their long-term use rights to overcome future threats.

Climate change,biological invasions,and the shifting distribution of Mediterranean fishes: A large‐scale survey based on local ecological knowledge

Climate change and biological invasions are rapidly reshuffling species distribution, restructuring the biological communities of many ecosystems worldwide. Tracking these transformations in the marine environment is crucial, but our understanding of climate change effects and invasive species dynamics is often hampered by the practical challenge of surveying large geographical areas. Here, we focus on the Mediterranean Sea, a hot spot for climate change and biological invasions to investigate recent spatiotemporal changes in fish abundances and distribution. To this end, we accessed the local ecological knowledge (LEK) of small‐scale and recreational fishers, reconstructing the dynamics of fish perceived as “new” or increasing in different fishing areas. Over 500 fishers across 95 locations and nine different countries were interviewed, and semiquantitative information on yearly changes in species abundance was collected. Overall, 75 species were mentioned by the respondents, mostly warm‐adapted species of both native and exotic origin. Respondents belonging to the same biogeographic sectors described coherent spatial and temporal patterns, and gradients along latitudinal and longitudinal axes were revealed. This information provides a more complete understanding of the shifting distribution of Mediterranean fishes and it also demonstrates that adequately structured LEK methodology might be applied successfully beyond the local scale, across national borders and jurisdictions. Acknowledging this potential through macroregional coordination could pave the way for future large‐scale aggregations of individual observations, increasing our potential for integrated monitoring and conservation planning at the regional or even global level. This might help local communities to better understand, manage, and adapt to the ongoing biotic transformations driven by climate change and biological invaders.     

Influence of lunar cycle on catches of spiny lobster Panulirus argus (Decapoda: Palinuridae) in the Gulf of Batabanó, Cuba

Many biological processes such as reproductive and migratory behaviours have been associated with moon cycles. In this study, the nocturnal light levels associated with lunar cycle (INT) were correlated with daily catch rate of lobster P. argus, during seven lunar months of 2002 fishing period, to determine a possible relationship between these variables. The lobster catches were obtained from three fishing companies that develop their activities in the Gulf of Batabanó: EPICOL that fishes in Coloma area; PESCAHABANA in Batabanó area and PESCAISLA in Isla area. Daily catch per boat (CDB) was used as a measurement of daily catch variations (catch rate). The correlation was analyzed showing it in chronological graphs based on average of CDB per lunar phases, comparing lobster catch rate per lunar phases -with the Kruskal-Wallis test-. Spearman rank correlation coefficient and cross correlation techniques were also applied. Similarities between lobster catch rate and the lunar cycle were not found. Spearman rank correlation coefficient was modularly smaller than 0.1 in all cases and demonstrated quantitatively that correlation between CDB and INT does not exist. Kruskal-Wallis test detected differences only in Batabanó area but not when making the analyses for the whole Gulf of Batabanó. Finally, the cross correlations do not detected significance in any zone, as well. It is concluded that, in opposition to what other authors have reported, the catch rates of P. argus and the lunar cycle did not show significant correlation in the Gulf of Batabanó. This trend was independent of the fishing art, which varied according to the time of the year that was analyzed.     

LCA of Danish Fish Products. New methods and insights (9 pp)

Goal, Scope and Background This article presents the main results from a PhD dissertation about environmental impacts from Danish fish products. The focus is on LCA results for flatfish, but the article also gives an overview of screenings of other fish species. Furthermore, it includes an analysis of the energy consumption in the fishing stage – as a function of fish species and fishing methods. Alternative impact categories that have not been included in the quantitative LCA and policy perspectives are elaborated in the discussion part of the paper. Methods The study represents a consequential LCA approach (opposed to attributional) and the functional unit is one kg consumed flatfish filet in units of 300 gram (cardboard boxes). Data are obtained from statistics, interviews, literature, and databases – mainly ETH-ESU 96 and the Danish LCA food database. The EDIP 97 method has been applied for life cycle impact assessment (LCIA) and the results have been verified by Ecoindicator 99. Results The results of the flatfish LCA show that the fishing stage has the largest impact potential for the investigated impact categories. This is mainly due to a relatively high fuel consumption and significant emissions of biocides from anti-fouling agents (contributing to ecological toxicity). But large reductions in fuel intensity (fuel consumption per kg caught fish) can be obtained by changing the type of fishing gear – particularly in flatfish fisheries. The consumption and retail stages represent significant impact potentials as well, while processing is insignificant. LCA screenings of other fish species show the same picture, but there are cases (herring, mackerel and mussels) where the fishing stage is less important, while the opposite is the case for processing – mainly due to energy intensive packaging materials. Discussion A limited number of impact categories have been investigated, but a 'qualitative' LCA, focusing on other fishery specific impacts, emphasises that the fishing stage is indeed the overall most important. In this regard, it is argued that fuel requirements in many cases are proportional to environmental impacts related to 'discard' and 'seafloor damage'. Hence, it is worth focusing on energy for many reasons. In a policy context, it is a paradox that mainly the fish processing industry has been subjected to environmental regulations. Recommendation and Perspective Future scenarios indicate that energy consumption will remain one of the most important environmental aspects in the fishing stage – partly due to regulations of anti-fouling biocides (e.g. TBT) and partly because of the continued depletion of fish stocks. From an environmental policy perspective, it is therefore recommended to broaden the perspective of existing fishery regulations and increase the focus on fishing gear and energy in the primary production (fishing stage).     

Harvest Pressure on Coastal Atlantic Cod (Gadus morhua) from Recreational Fishing Relative to Commercial Fishing Assessed from Tag-Recovery Data

Marine recreational fishing is a popular outdoor activity. However, knowledge about the magnitude of recreational catches relative to commercial catches in coastal fisheries is generally sparse. Coastal Atlantic cod (Gadus morhua) is a target species for recreational fishers in the North Atlantic. In Norway, recreational fishers are allowed to use a variety of traps and nets as well as long-line and rod and line when fishing for cod. From 2005 to 2013, 9729 cod (mean size: 40 cm, range: 15–93 cm) were tagged and released in coastal Skagerrak, southeast Norway. Both high-reward (NOK 500) and low-reward tags (NOK 50) were used in this study. Because some harvested fish (even those posting high-reward tags) may go unreported by fishers, reporting rates were estimated from mark-recovery models that incorporate detection parameters in their structure, in addition to survival and mortality estimates. During 2005 to 2013, a total of 1707 tagged cod were recovered and reported by fishers. We estimate the overall annual survival to be 33% (SE 1.5). Recreational rod and line fishing were responsible for 33.7% (SE 2.4) of total mortality, followed by commercial fisheries (15.1% SE 0.8) and recreational fixed gear (6.8% SE 0.4). Natural mortality was 44.4% (SE 2.5) of total mortality. Our findings suggest that recreational fishing—rod and line fishing in particular—is responsible for a substantial part of fishing mortality exerted on coastal cod in southern Norway.     

Resource Conflicts: Challenges to Fisheries Management at the São Francisco River,Brazil

The paper describes factors influencing artisanal fisheries at the São Francisco River in Brazil as an example of the challenges of managing socially and economically valued common-pool resource systems. A rapid assessment of problems affecting São Francisco River fisheries in 10 communities was carried out in 2003, representing the upper, middle, and lower river portions. Field visits, interviews, focus group discussions and a literature survey allowed us to map socioeconomic and environmental factors important to the fisheries, including conflicts and tensions between stakeholders. Federal, state, and municipal governments, industries, farmers, hydroelectric companies, and urban and rural populations all have a stake in river use. Traditional fishers are the most disadvantaged of these stakeholders. With declining fish populations, most of the fishing communities surveyed are now poor, socially excluded, and with few alternative livelihood options. The stakeholders involved in access and use conflicts are artisanal fishers, professional fishers, sport fishers, farmers, enforcement and regulatory agencies, and hydroelectric companies. Traditional fishers have close ties to the river and its environment and they are usually not invited to contribute to resource management decisions. We recommend changes to management structures involving the fishing communities that are essential to resolve the major conflicts and to improve equity and sustainability of artisanal fisheries.     

Run timing of pelagic fishes in Gulf of St Lawrence: area and species effects

Run timings of four ubiquitous pelagic fishes in the Gulf of St Lawrence were compared for area and year effects. Run timing of alewife, Alosa pseudoharengus (Wilson), smelt, Osmerus mordax (Mitchill), and Atlantic salmon, Salmo salar L., was estimated at index rivers, and time of arrival of herring, Clupea harengus L., on spawning grounds was estimated from gillnet fisheries located around the Gulf, 1978–87. Time of pelagic fish migrations had strong species and area effects, but weak year effects. The species had their own unique migration times and durations, and could be divided into two groups: herring and smelt, which arrived in all areas of the Gulf at the same time; and alewife and salmon, which had significant area effects. Environmental data were not correlated with run timing. There was little annual variation in run timing among early-run species; only alewife had significant year effects. There was annual variation in the timing of late-run species, but it was not correlated with proximate environmental factors. Because run timing is an easily defined stock characteristic, observations over large areas and many years might be useful for understanding the impact of large-scale environmental changes on natural populations.