Mapping global fisheries: sharpening our focus

Mapping global landings is an important prerequisite for examining causal relationships between fishing and ecological change. Landing statistics, typically provided with poor spatial precision, can be disaggregated into a grid system of spatial cells (30 min ×30 min) using a rule‐based approach and ancillary data about distributions of fished taxa and fishing access of reporting countries. Presentation of time series catch composition is then possible for many types of marine areas including biogeochemical provinces, large marine ecosystems and exclusive economic zones.     

Are fishers poor? Getting to the bottom of marine fisheries income statistics

Fishers’ economic status is hard to assess because fisheries socio‐economic data, including earnings, are often not centrally available, standardized or accessible in a form that allows scaled‐up or comparative analyses. The lack of fishing income data impedes sound management and allows biased perceptions about fishers’ status to persist. We compile data from intergovernmental and regional data sets, as well as case‐studies, on income earned from marine wild‐capture fisheries. We explore the level and distribution of fishers’ income across fisheries sectors and geographical regions, and highlight challenges in data collection and reporting. We find that fishers generally are not the poorest of the poor based on average fishing income from 89 countries, but income levels vary widely. Fishing income in the large‐scale sector is higher than the small‐scale sector by about 2.2 times, and in high‐income versus low‐income countries by almost 9 times. Boat owners and captains earned more than double that of crew and owner‐operators, while income from fisheries is greater than that from agricultural work in 63% of countries in this study. Nonetheless, incomes are below national poverty lines in 34% of the countries with data. More detailed fishing income statistics is needed for quantitative scientific research and for supporting socio‐economic policies. Key gaps to address include the lack of a centralized database for fisheries income statistics and the coarse resolution at which economic statistics are reported internationally. A first step to close the gap is to integrate socio‐economic monitoring and reporting in fisheries management.     

BMEY as a fisheries management target

This paper evaluates the implications of managing fisheries to achieve a B_MEY target, or a biomass level that maximizes net economic returns in the fishery, and discusses the role of private ownership and the trade‐offs between economic and conservation benefits in this setting. The paper shows how a B_MEY target can be used to: (i) determine relative employment and profitability measures; (ii) account for both the harvesting and processing sectors; and (iii) incorporate the interests of consumers and producers of fish. The profits–employment trade‐off of adopting a B_MEY target vs. a traditional B_MSY target is calculated using a model and data from the Western and Central Pacific tuna fisheries (WCPTF), while a generic bioeconomic model is constructed to show numerical values of B_MEY from including processing and/or retail sectors and the consumer benefits of harvesting fish. For the WCPTF, results show that the long‐term gains per job lost from pursuing a B_MEY target are worth several times the value of the average GDP per capita of Pacific Island Countries. The generic bioeconomic model shows that including a processing and/or retail sector, as well as measures of consumer benefit, lowers the B_MEY target. However, there remains a broad range of parameter values for which B_MEY is still greater than biomass at maximum sustainable yield, or B_MSY. The paper also illustrates cases where B_MEY > B_MSY at different values of the price elasticity of demand, margins for processing and/or retail sectors and values of the discount rate.     

Predicting the growth of gilthead sea bream (Sparus aurata L.) farmed in marine cages under real production conditions using temperature- and time-dependent models

The growth of gilthead sea bream ( Sparus aurata ) has been studied considering five multiple exponential regression models using data from 20 lots of gilthead sea bream growing in 20 marine cages from a Mediterranean commercial fish farm. The final weight ( W _f) of fish was predicted in relation to the initial weight ( W _i), time ( n ) and temperature ( T ), or the sum of effective temperatures (∑ T _ef). The estimated weight results from the simulation using the five models have been compared with the real final weight values using the mean of the absolute values of the prediction errors in short and long term (the precision value). All models presented a high determination coefficient, above 96%, and good prediction values in the short term. Regression models were tested using data from six new cages. The best models for predicting the growth of sea bream long term were the ones where final weight is expressed in relation to the initial weight and the sum of effective temperature,     and     obtaining long-term prediction errors 12.9% and 10.7% respectively.     

Fisheries of two tropical lagoons in Ghana, West Africa

Abstract  The fisheries of two coastal lagoons, Keta and Songor, were studied as part of Ghana Coastal Wetlands Management Project (GCWMP) aimed at sustainable exploitation of wetland resources. Fish samples were obtained with seine nets and cast net as well as from local fishermen. Water quality parameters (pH, dissolved oxygen, temperature and turbidity) were similar in the two lagoons, except for salinity, which was significantly different ( P  < 0.001). Despite their close geographical proximity, the two lagoons supported different fish assemblages with the blackchin tilapia, Sarotherodon melanotheron Rüppell, and the redchin tilapia, Tilapia guineensis (Bleeker), being the most important commercial fishes in both lagoons. The number of individuals for each species in Songor Lagoon were far more abundant, with densities several orders of magnitude higher than in Keta Lagoon. However, both species were significantly larger ( P  < 0.01) in the latter [15–121 and 25–157 mm standard length (SL)] than in the former lagoon (30–102 and 15–95 mm SL) for S. melanotheron and T. guineensis respectively. Over-fishing, use of small-size mesh nets, limited mixing of marine and fresh water were some of the factors limiting fish production in both lagoons.     

Beyond Individual Transferrable Quotas: methodologies for integrating ecosystem impacts of fishing into fisheries catch rights

While there has been a growing concern for the adverse ecological impacts of fishing, progress on incorporating these into operational fisheries management has been slow. Many fisheries management organizations have addressed the problem of overharvesting and over‐capitalization first. In this domain, the question of access regulation has gained growing recognition as a key dimension of fisheries sustainability, leading to recommendation and progressive implementation of rights‐based systems, in particular Individual Transferrable Quotas (ITQs). While adjustments in fishing capacity resulting from the implementation of these systems may entail a reduction in some unwanted ecosystem impacts of fishing, it is also recognized that they will not be sufficient to achieve the ecological outcomes increasingly demanded by the global community. There is thus a need to examine the possibilities for a common management framework for dealing with both over‐capitalization of fisheries and adverse ecological effects of fishing. In this paper, we examine the feasibility of incorporating greater ecosystem goods and services into ITQ policy instruments initially designed with a narrow focus on commercial target species. We consider the advantages and limitations of alternative approaches in this respect and identify some of the practical issues associated with the different alternatives, in particular the underpinning knowledge requirements. We argue that given the need for increasingly streamlined management processes, further investigation into practical ways forward in this domain is crucial if management of fisheries is to achieve economic efficiency while fully encompassing the ecologically sustainable development objectives of ecosystem‐based fisheries management.     

Trouble on the reef: the imperative for managing vulnerable and valuable fisheries

Reef fishes are significant socially, nutritionally and economically, yet biologically they are vulnerable to both over‐exploitation and degradation of their habitat. Their importance in the tropics for living conditions, human health, food security and economic development is enormous, with millions of people and hundreds of thousands of communities directly dependent, and many more indirectly so. Reef fish fisheries are also critical safety valves in times of economic or social hardship or disturbance, and are more efficient, less wasteful and support far more livelihoods per tonne produced than industrial scale fisheries. Yet, relative to other fisheries globally, those associated with coral reefs are under‐managed, under‐funded, under‐monitored, and as a consequence, poorly understood or little regarded by national governments. Even among non‐governmental organizations, which are increasingly active in tropical marine issues, there is typically little focus on reef‐associated resources, the interest being more on biodiversity per se or protection of coral reef habitat. This essay explores the background and history to this situation, examines fishery trends over the last 30 years, and charts a possible way forward given the current realities of funding, capacity, development patterns and scientific understanding of coral reef ecosystems. The luxury live reef food‐fish trade is used throughout as a case study because it exemplifies many of the problems and challenges of attaining sustainable use of coral reef‐associated resources. The thesis developed is that sustaining reef fish fisheries and conserving biodiversity can be complementary, rather than contradictory, in terms of yield from reef systems. I identify changes in perspectives needed to move forward, suggest that we must be cautious of ‘fashionable’ solutions or apparent ‘quick fixes’, and argue that fundamental decisions must be made concerning the short and long‐term values of coral reef‐associated resources, particularly fish, for food and cash and regarding alternative sources of protein. Not to address the problems will inevitably lead to growing poverty, hardship and social unrest in many areas.     

New perspectives on aquarium fish trade

ABSTRACT:   Since the 1990s, the international market for importing aquarium fish is suspicious of stock coming from South-East Asia. Fish catches are still executed with cyanide-based toxic products. In the present paper, the potential of the French Polynesian Islands to develop a marine aquarium fish business with a new approach is explored. Coral reef fish are captured at the larval stage with crest nets, then larvae are reared in aquaria before being put on the world ornamental fish market. This approach offers several advantages: (i) larvae are captured with a passive system placed on the reef crest (crest net) that does not destroy the environment and limits the stress on collected larvae; (ii) larvae are then put into farmed basins that allow them to be controlled sanitarily; and (iii) larvae are weaned at the farm and fed rapidly with artificial food. This method increases survival rates as it eliminates the food acclimatization problem of fish captured at adult stage (main cause of fish mortality in aquaria). Overall, reared larvae will constitute a new product in terms of species, sizes and quality of ornamental fish on the aquarium market.