The silver scabbardfish Lepidopus caudatus is a mesopelagic species living on the shelf and slope down to 600 m in temperate seas all around the world. In the Mediterranean, the species is caught mainly by longlines with a marked seasonality. In the early 90s in the Strait of Sicily (Central Mediterranean Sea), a new fishery targeting L. caudatus was developed. This fishery uses an ad hoc pelagic trawl gear called “spatolara.” Vessels using spatolara have increased from 1 in 1993 to 10 in 2007 with a growth of catches of up to 1,200 tons in 2011. Development of this fishery was not regulated by any specific management measures and, due to the progressive reduction of catch to 169 tons, only one vessel was active in 2018. The availability of catch and biomass indices from trawl survey since the beginning of trawling exploitation allowed providing the first assessment of the state of L. caudatus stock in the Central Mediterranean (GFCM Geographical Sub-Area 16) by using data-limited methods. Catch-Maximum Sustainable Yield (CMSY) and Bayesian State Space Schaefer model (BSM) were fitted to landings and abundance indices (2004–2018). The Abundance-Maximum Sustainable Yield model (AMSY) was also applied to survey data from 1994 (1 year after the start of the spatolara fishery) to 2018 to further corroborate the results. BSM prediction of biomass levels was just above 50% of BMSY, whereas AMSY estimated the current stock levels below 50% of BMSY. The BSM was used for forecasting B/BMSY and catches under different fishing scenarios. Although current exploitation was very close to FMSY, more than a decade would be needed to rebuild the stock to biomass levels producing MSY. A faster rebuilding could be achieved by fishing at least 80% of FMSY, with minimal loss in yield over the next 5–8 years. Following the development of a new fishery since the beginning, the study provides a further example of how unregulated exploitation leads to a heavy overfished state of stock and collapse of fishing activities.
Fisheries and Fisheries Management
Fisheries and Oceans Canada (DFO) established the Sustainable Fisheries Framework (SFF) in 2009 to help meet Canada’s international commitments towards sustainable fisheries management. The SFF is a suite of policies and tools intended to ensure the precautionary approach (PA) is incorporated into fisheries management. Seven years later (2016) a federal government audit by the Canadian Commissioner of the Environment and Sustainable Development (CESD) found that although DFO had identified key components necessary for successful fisheries management in the SFF, it had failed to put these components in place for many stocks and did not always apply them even when they were in place. The DFO response to the CESD audit included a commitment to develop work plans with deliverables outlining priorities and timelines for implementing key aspects of the SFF: reference points, harvest control rules, management plans and rebuilding plans for critically depleted stocks. The present study evaluated progress towards meeting this commitment and found that only 38% of the expected products were completed, 14% are in progress, 40% have progress delayed and are not proceeding as anticipated, while the remaining 8% were suspended. This weak performance highlights a larger trend of inadequate and slow implementation of legislative and policy tools in the management of Canada’s fisheries and oceans. With declining health status of Canadian stocks and less than half of critical stocks with rebuilding plans, these failures are having a significant impact on the ability of good policy to promote the long-term health of Canada’s fisheries and fishing communities.
Formal and informal institutions govern fisheries around the world. Yucatan’s sea cucumber fishery is not an exemption, the sudden and fast development of the fishery in 2010 has motivated the creation of informal and illegal forms of organization. The prices, buyers’ interest and the fishing effort substantially increased, being followed by illegal fishing-fishers and traders, creating informal fishing-trade channels and severe social and biological concerns. This article aims to give account of the emergence and dynamics of the informal institutions which currently dominate this fishery. It was sought to identify the extent to which rules and regulations are not being respected and how they are affecting fish resources and coastal communities. We considered the case of the port of Sisal, Yucatan, Mexico to illustrate our argument and here we applied a mixture of qualitative and quantitative methodologies including informal and in-depth interviews applied to 17 key informants, a questionnaire applied to 47 fishers and an estimation of the degree of compliance from three of the main management measures. Socio-biological negative impacts were identified in Yucatan’s coastal communities and its fisheries. Foreign buyers and local middlemen exert high pressure on fishers to exceed the quota and catch the highest possible volumes facilitating the fisheries decline. This and the growing economic interest motivated the development of strong informal institutions supporting illegal fishing and informal trade. Social problems emerged and women were particularly affected. The economic power of the fishery is likely to overcome any type of governance structure. The enforcement of entry rules was not effective, so the governance base was around informality and illegal actions. Local and foreign buyers are exerting pressure to increase the catch volume thus it is recommended that rules and regulations be directed at buyers and exporting companies rather than at fishers.
Ecological disturbances may result in mortality events that alter biotic communities and ecosystems. In many coastal zones disturbances are increasing, including algal blooms and fish kills. These two disturbances are often related, with blooms releasing toxins or depleting oxygen, ultimately killing fish. Depending on the intensity, duration, and geographic extent of an algal bloom, the fish community can take days to years to recover from disturbances. To explore the relationship among environmental disturbances, sport fish, and forage fish communities, this study examines a non-toxic brown algal bloom (Aureoumbra lagunensis) occurring from December 2015 through March 2016. Using an ensemble modelling framework combining generalized linear models (GLM), Bayesian modelling, and Bayesian structural equation modeling (SEM), this complementary framework helped elucidate complex relationships among environmental variables and the fish community following a disturbance. The algal bloom crashed over a three-day period in March 2016 and resulted in a fish kill when dissolved oxygen concentrations dropped below hypoxic levels (DO < 2 mg/L). The bloom and subsequent fish kill led to shifts in both forage and sport fish communities, and their relationships, when compared to non-disturbed years. Both sport fish and forage fish abundances decreased following the bloom, but the response of the forage fish community was more rapid. When looking at direct correlations between individual sport fish and forage fish community metrics during the bloom, a large amount of variation in sport fish abundance was explained by forage fish abundance (R2 = 0.34). Also, the variation in forage fish abundance was explained well by pH (R2 = 0.72). Forage fish community dynamics were more closely related to water quality metrics than sport fish communities during non-disturbed periods. However, during this algal bloom, sport fish community dynamics were more closely associated with water quality metrics than forage fish community dynamics. Furthermore, sport fish community dynamics were strongly related to bloom dynamics during the three months prior to the fish kill. In the three months following the kill, the forage and sport fish communities were less strongly linked than in non-disturbed years. These large shifts in community dynamics and relationships following a disturbance suggest both forage and sport fish communities, food webs, and trophic dynamics may be at increasing risk of crossing ecological thresholds as algal blooms become more common in coastal ecosystems.
Genetic individual assignment of river stock of origin of mixed stock catch fish offers a tool to analyze size differences among river stocks. Data on the genetically identified river stock of origin of individual fish from commercial mixed stock catches were used to compare the catch size-at-age of mature Atlantic salmon catch fish (Salmo salar) from different rivers in the Baltic Sea. In this application of genetic mixed stock modeling, individual assignments of the river stock of origin were analyzed together with length- and weight-at-age data for individual catch fish. The use of four genetic stock identification based methods was compared for defining the length distributions of caught mature salmon in different river stocks. The catch data included information on maturing salmon in the northern Baltic Sea over the years 2000–2013. DNA microsatellite data on 17 loci and information on the smoltification age were used to assign spawners to their stock of origin. All of the compared methods for using probabilistic stock of origin data in our case yielded very similar estimates of the final mean length distributions of the stocks. The Bayesian mixture model yielded slightly more conservative estimates than the direct probability method, threshold method, or the modified probability method. The catch size between spawners of a same sex and age from river stocks differed significantly and the differences were large. The mean catch weight of 1-sea-winter old mature males in different rivers varied from 1.9 kg to 2.9 kg, from 5.1 kg to 7.5 kg for 2-sea-winter old males, from 5.0 kg to 7.2 kg for 2-sea-winter old females, and from 8.2 kg to 10.8 kg for 3-sea-winter-old females. The mean size of caught wild salmon spawners in each year-class was on average smaller than that of the hatchery-reared and sea ranched stocks.
Overfishing is notorious for triggering population collapses and disrupting marine biological functioning worldwide. To counter such a threat, policy-makers have created and implemented multiple management strategies, but most were incapable to prevent the decline of several key species. Here, we discuss a new management strategy in force since June 2019 in Brazil that aims to deter the overfishing of parrotfish species of the genera Scarus and Sparisoma. This innovative strategy, here referred to as inverted management, allows the capture of endangered parrotfish species inside management areas, such as partially protected marine areas—MPAs, but bans it elsewhere. This initiative is supposed to be built in a partnership among the government, scientists, managers, and fishers. If implemented correctly, endangered species would recover in the much larger area outside MPAs, and fishers would benefit from the conservation-value of the scarce and valued product. However, to succeed, the strategy depends on the adoption of a series of challenging management rules that are not currently being enforced along an extensive coastline. So far, few MPAs have incorporated rules for endangered species in their management plan, and those that have done so have no plans or the means to enforce them. Therefore, fishing of endangered species is currently ongoing without any management or monitoring in the entire Brazilian coast. Concerned with the challenges to develop plans to recover populations of endangered species faced by Brazilian managers, we suggest wide communication and a ban on the fisheries until management plans are implemented. Additionally, we suggest that the effectiveness of the inverted management strategy for parrotfishes should be assessed before it’s applied to other endangered species.
Sublittoral rocky reef habitats host important ecological communities in UK waters, but their ecological condition is difficult to monitor. Monitoring methods based on seabed imagery data are prone to inconsistencies in both the identification and enumeration of species, which is a major hurdle in detecting meaningful ecological change. To overcome this problem, our study used a single monitoring dataset, collected using one standard method at the Pisces Reef Marine Protected Area (MPA) in 2016. We identified which method of data extraction from seabed imagery is best able to detect change along a gradient of anthropogenic resuspended sediments, which represents a pressure on the epifaunal community. We modelled the spatial distribution of the pressure, caused by nearby fishing activity, using an approach based on individual Vessel Monitoring System (VMS) ping data, rather than spatially homogenised data aggregated to a grid cell. We found that up to 22% of the biological variability across the three reef areas within the MPA is explained by the measured and derived environmental variables. The response of the epibenthic community at Pisces Reef MPA to the resuspended sediments pressure gradient is masked by commonly used univariate metrics such as species diversity and abundance of individuals. Conversely, a Threshold Indicator Taxa Analysis (TITAN) identifies community-level change caused by a low level of modelled resuspended sediments pressure. We found that a 0.05 decimal degree grid cell of seabed within 1 km of the MPA boundary, swept by demersal fishing gear as little as five times per year on average, can elicit such a community response. The data extraction metric best able to detect this change in the sublittoral rock community is the frequency of occurrence of taxa in images with an average field of view of 0.7 m2, using a 25-cell grid. More traditional metrics extracted from seabed imagery, such as raw counts and percentage cover estimates, are less sensitive to detecting such community change. The TITAN also identified taxon-level responses to the pressure gradient that could be considered for future monitoring programmes. The solitary coral genus Caryophyllia and cup-like sponges show a sharp and strong negative response to pressure exposure, and could represent a starting point for a future monitoring programme of UK sublittoral rock habitats. The implications for future monitoring are discussed, including survey design, environmental and biological data collection and improved pressure modelling.
Climate change is already affecting the distributions of marine fish, and future change is expected to have a particularly large impact on small islands that are reliant on the sea for much of their income. This study aims to develop an understanding of how climate change may affect the distribution of commercially important tuna in the waters around the United Kingdom’s Overseas Territories in the South Atlantic. The future suitable habitat of southern bluefin, albacore, bigeye, yellowfin and skipjack tunas were modelled under two future climate change scenarios. Of all the tunas, the waters of Tristan da Cunha are the most suitable for southern bluefin, and overall, the environmental conditions will remain so in the future. Tristan da Cunha is not projected to become more suitable for any of the other tuna species in the future. For the other tuna species, Ascension Island and Saint Helena will become more suitable in the future, particularly so for skipjack tuna around Ascension Island, as the temperature and salinity conditions change in these areas. Large marine protected areas have been designated around the territories, with those in Ascension and Tristan da Cunha closed to tuna fishing. Although these areas are small relative to the whole Atlantic, these model projections could be useful in understanding whether this protection will benefit tuna populations into the future, particularly where there is high site fidelity.
In many parts of the world, particularly remote and underdeveloped regions, reports of fisheries catch, effort, and landing data are limited. In order to implement effective fishing regulations to protect natural stocks, understanding fishing pressure, key target species, catch composition, and value of each species is vital. In regions where published data is limited, and the sampling of numerous small boats and landing sites is not feasible, fish market surveys represent an opportunity to obtain key fisheries data. This study therefore aims to obtain species-specific prices and market composition for fish landed in the central Red Sea by surveying local fish markets. We conducted 11 surveys at two major Red Sea fish markets to ascertain key fisheries metrics using market data as a proxy for catch data. Results indicate that a high proportion of the market composition is generated by 46 species from six family-level groups, Serranidae, Labridae, scarine labrids, Carangidae, Lethrinidae, and Lutjanidae, contributing to 87 % of the total market biomass. Species-specific values ranged from 4.50 USD/kg to 26.44 USD/kg, with market surveys highlighting the economic value of three local serranid species: Plectropomus pessuliferus marisrubri, Plectropomus areolatus and Variola louti, all valued at more than 25 USD/kg, and a labrid: Cheilinus undulatus, valued at 26.44 USD/kg. The Serranidae family represents 47 % of the total biomass and 55 % of the potential revenue in the market, while also indicating potentially overfished reefs due to the high occurrence of smaller species and undersized individuals of higher priced serranid species. Many of the high-valued serranids were below the size at sexual maturity. Target species exhibited small body size and decreasing abundance, potentially indicating a “shrinking baseline” scenario occurring in the Saudi Arabian artisanal coral reef fishery. These results indicate that introducing effective fisheries legislation and management is necessary for the longevity and sustainability of the reef-based fishery in the Saudi Arabian Red Sea. Implementing catch quotas, size limits, and seasonal restrictions are potential mechanisms that could be used to facilitate positive change within this vulnerable fishery.
The recent establishment of the “landing obligation” under the reformed EU Common Fishery Policy has the twofold objective of reducing the excessive practice of discarding unwanted catch at sea and encouraging more selective and sustainable fisheries. Within this context, the awareness of the spatial distribution of potential unwanted catches is important for devising management measures aimed to decrease discards. This study analyzed the distribution of Hot Spot density areas of demersal fish and crustaceans below the Minimum Conservation Reference Size (MCRS) in four different southern European seas: continental Portuguese coast, Catalan Sea, South of Sicily, Liguria and northern Tyrrhenian Seas using both bottom trawl survey data and information on the spatial distribution of commercial fisheries. Critical areas for discarding were identified as zones where the highest densities of individuals below MCRS were consistently recorded throughout a series of years. Results clearly showed a patchy distribution of undersized individuals in each investigated area, highlighting the overlap between high density patches of both discards and fishing effort. The present findings provide a relevant knowledge for supporting the application of spatial-based management actions, such as the designation of Fisheries Restricted Areas (FRAs), in order to minimize the by-catch of undersized specimens and improve the sustainability of demersal fisheries.