To evaluate the impacts of fishing on marine ecosystems, the total extraction of fish must be known. Putting a figure on total extraction entails the difficult task of estimating, in addition to reported landings, discards, illegal and unmandated catches. Unreported catches cast various types of shadow, which may be tracked and estimated quantitatively. Some shadows of unreported catches are reviewed, for example, an innovative, well-funded NGO publicizes illegal catch in the Southern Ocean. For various reasons, official figures often have the implicit but unacceptable assumption that such categories are null. We present an estimation procedure based on adjustment factors taken from observer reports, correspondents and published information that track changes in a regulatory regime, and hence reflect incentives and disincentives to misreport. Monte Carlo simulations address uncertainty using multiple sources of information to provide upper and lower estimates. Once in place, this method provides preliminary estimates that may be refined without disruption. The method is demonstrated for fisheries in Iceland and Morocco. We use a ‘by-species’ approach for Icelandic cod and haddock, while the Moroccan catch is divided into demersal and pelagic categories. Results suggest that Icelandic cod catches may have been underestimated by between 1 and 14% at different times, and haddock by between 1 and 28%. Underestimation of Moroccan catches appears to have been as much as by 50%. These case studies show that it is possible to obtain estimates of misreporting, even when direct data are lacking. Our method encourages transparency because sources of information are presented so that uncertain values are easily identified, offering a basis for comment, collaboration and refinement in estimating illegal and unreported fishing.

/pdf/estimating-illegal-and-unreported-catches-from-marine-3fe2clq2tu.pdf

Estimating illegal and unreported catches from marine ecosystems: a basis for change

http://digital.csic.es/bitstream/10261/53738/3/Life_history_Loligo.pdf

The life history of Loligo vulgaris and Loligo forbesi (Cephalopoda: Loliginidae) in Galician waters (NW Spain)

Body size at sexual maturity, egg-size distributions, and potential reproductive output have been estimated for female and male squid, Loligo forbesi Steenstrup, off the west coast of Scotland. Two size modes at maturity were found in both sexes, but separation into size cohorts was more pronounced in males (180 and 350 mm mantle length, ML). Preliminary ageing studies based on statolith ring-counts suggest that these size modes are not due to different age groups at breeding. Females have a single size mode of mature eggs in the proximal oviduct, but may have at least two size modes of eggs within the ovary. This finding is interpreted as evidence of batch-spawning in this squid. There was a weak relationship between total egg numbers (range 1000 to 16000) and body size (range 196 to 318 mm ML) and between mature egg size and body size. Males showed a strong positive relationship between spermatophore length and body length but a weak relationship between total number of spermatophores and body size. The results are discussed in the context of flexibility of breeding strategies in the loliginids and variety of life-cycle patterns.

Flexible reproductive strategies in the squid Loligo forbesi.

Fisheries landing statistics from broad statistical reporting areas were mapped as catches with a resolution of 30 minutes of longitude x 30 minutes of latitude. The procedure involved the progressive disaggregation of the statistics, firstly to provide poorly defined records with a better taxonomic identity, and secondly by using a rulebased process involving databases of known distributions of taxa, oceanographic features and of the areas where reporting countries are permitted to fish, in order to spatially disaggregate the data. Maps prepared for reporting years 1950 until 1999 showed trends in the spatial distribution of fisheries catches, provided a valuable means of examining other questions such as interactions between fishing and marine mammals, and provided descriptions of the global catch from large marine ecosystems. Catch maps prepared for the North Atlantic are illustrated and were used in the formation of ecological models and in the preparation of maps of catch value.

Fisheries Impacts on North Atlantic Ecosystems : Catch, Effort and National/Regional Data Sets

The biological communities of the Atlantic continental shelf adjacent to the southeastern United States are well known, but this knowledge is not integrated into a cohesive description of that region. We constructed a preliminary food web model of this area using Ecopath with Ecosim, as a way to initiate a long-term process of integrating this knowledge, learning more about the structure and resiliency of the system, and helping to guide research priorities in the future. The current model is considered to be a first iteration that can be used as a vehicle to stimulate a more rigorous refinement effort in the near future. The ecologically defined area covered by this model extends from Cape Hatteras, North Carolina to the easternmost extent of the Florida Keys, and from the intertidal zone (or the entrance of estuarine systems) to the 500 m isobath. The time period characterized by this preliminary model is the four years from 1995 to 1998.

Mohammed Baddyr

Papers

The biology of the squid Loligo vulgaris in relation to the artisanal fishing site of Tifnit, Morocco.