Discards represent one of the most important issues within current commercial fishing. It occurs for a range of reasons and is influenced by an even more complex array of factors. We address this issue by examining the data collected within the Danish discard observer program and describe the factors that influence discarding within the Danish Kattegat demersal fleet over the period 1997 to 2008. Generalised additive models were used to assess how discards of the 3 main target species, Norway lobster, cod and plaice, and their subcomponents (under and over minimum landings size) are influenced by important factors and their potential relevance to management. Our results show that discards are influenced by a range of different factors that are different for each species and portion of discards. We argue that knowledge about the factors influential to discarding and their use in relation to potential mitigation measures are essential for future fisheries management strategies.
To reduce the practice of discarding commercially fished organisms, several measures such as a discard ban and extra allowances on top of landings quotas (“catch quota”) have been proposed by the European Commission. However, for their development and successful implementation, an understanding of discard patterns on a European scale is needed. In this study, we present an inter-national synthesis of discard data collected on board commercial, towed-gear equipped vessels operating under six different national flags spanning from the Baltic to the Mediterranean Seas mainly between 2003 and 2008. We considered discarded species of commercial value such as Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), European hake (Merluccius merluccius), and European plaice (Pleuronectes platessa). Comparisons of discard per unit effort rates expressed as numbers per hour of fishing revealed that in the Mediterranean Sea minimum size-regulated species such as hake are generally discarded in much lower numbers than elsewhere. For most species examined, variability in discard rates across regions was greater than across fisheries, suggesting that a region-by-region approach to discard reduction would be more relevant. The high uncertainty in discard rate estimates suggests that current sampling regimes should be either expanded or complemented by other data sources, if they are to be used for setting catch quotas.
The Baltic cod (Gadus morhua) plays a very significant role in the Baltic Sea ecosystem being the major fish top predator and the most important commercial species for the Baltic Sea fishing industry. Consequently the management and understanding of the exploitation pattern of the stock is of major importance. Technical regulations, improving the selectivity of cod, have been a major management strategy and the Baltic Sea is likely to be the area where most fishing gear selectivity studies, focussing on size selectivity, have been conducted over time. The methodology for conducting and analysing selectivity data has been significantly improved in recent years. The subject is reviewed since the choice of methodology can have a significant effect on the interpretation of the outcome of selectivity experiments. Factors affecting the selectivity of trawl and gill nets are considered. Alternative ways to improve the size and species selectivity of trawls using selective devices are reviewed. Selectivity parameters from available literature are listed and the correlations of selectivity parameters to the mesh size for different gears are estimated. The historical legislation on selectivity is reviewed and the expected selectivity for trawls is estimated. Management considerations concerning the mortality of escaping and discarded fish and wider management impacts have to be considered if improving selectivity. The review is ended by conclusions including reflections on needed research in the future.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.