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Article Excerpt
Introduction
Fishing has been important to the livelihood of the Portuguese for centuries. Some coastal communities are almost totally dependent on fishing or related activities (DGPA, 1998). The nation's fishing grounds are delineated by an EEZ (Exclusive Economic Zone) of 1,700,000 [km.sup.2], encompassing both continental Portugal (with a coastline of 942 km) and two large insular regions surrounding the Azores and Madeira (DGPA, 1998).
Historically, fisheries have targeted elasmobranchs to supply the liver-oil or "squalene" market (Holts, 1988; Last and Stevens, 1994). Elasmobranchs have also been landed, and in many cases discarded, as the bycatch of other fisheries (Berkeley and Campos, 1988; Stevens, 1992). More recently, however, elasmobranchs have been targeted specifically to provide a source of protein in the form of meat and fins (Cailliet and Bedford, 1983; Holts, 1988).
The life history of elasmobranchs is characterized by slow growth rates, late maturity, long gestation periods, and the production of a small number of offspring (Holden, 1973; Pratt and Casey, 1990). These characteristics are customarily coupled with a distinctive predatory behavior (Gruber, 1982). Elasmobranchs therefore frequently represent an important "apex" role within their respective food web, and the depletion of their stocks could potentially cause a rapid and profound negative impact upon the ecosystem from which they are drawn (Gruber, 1982).
In addition, the nature of their life history frequently subjects elasmobranchs to a "high risk" of overfishing (Holden, 1973, 1974, 1977). Many publications highlight the inability of elasmobranchs to sustain strong fishing pressure for any extended period, as overfishing often translates into a rapid decline of population numbers (Pratt and Casey, 1990; Pepperell, 1992; Stevens, 1992; Musick et al., 1993; Sminkey and Musick, 1995). The delicate nature of elasmobranch populations emphasizes the need for effective conservation and management measures for this important taxonomic group.
In 1983, the Portuguese elasmobranch fishery expanded rapidly due to an increasing demand for shark by-products (i.e. oil, liver, etc.) and as the bycatch of an accelerated deep-sea teleost fishery (Nunes et al.(1)). In 1985, the demand for shark by-products peaked (oil prices reached US$4.00 - US$5.00 per liter) and then declined from 1987 to 1999 (oil prices decreasing to less than US$1.00 per liter) (Nunes et al.(1)). During the same period, the demand for elasmobranch flesh steadily increased, and at present, this represents the principal elasmobranch product marketed in Portugal. The flesh of these fishes is sold for human consumption either directly (in the case of many species of Rajidae and Squalidae) or indirectly (i.e. processed into other food products) (Nunes et al.(1)).
Portugal's elasmobranch fishery is not regulated, and thus there are no established size or catch quota limits. The "fishery" consists mainly of: 1) targeted deep-sea elasmobranch longlining; 2) targeted pelagic elasmobranch surface longlining; 3) bycatch of deep-sea elasmobranchs from black scabbardfish, Aphanopus carbo, longlining; 4) bycatch of pelagic elasmobranchs from teleost gill-netting, purse seining, and bottom trawling; and 5) bycatch of skates and rays from crustacean bottom trawling.
Despite their species' high-risk nature, elasmobranch fisheries have been little studied in this region. In Portugal, what little work has been published consists mainly of internal reports, most of which came from the Portuguese Marine Research Institute (Instituto de Investigacao das Pescas e do Mar, IPIMAR) (Silva (2,3,4), Silva and Pereira (5), and Figueiredo et al. (6)). This paper provides an introductory overview of the commercial Portuguese elasmobranch fishery and its evolution over the period between 1986 and 2001 and suggests possible avenues of future research.
Data Sources
The data for this study were obtained from the central commercial fishery authority for the Portuguese government (Direccao Geral das Pescas). Landed weights were totaled for each species, for all ports, for 1986-2001. Species whose landed weight exceeded 250 t are shown in Figure 1.
[FIGURE 1 OMITTED]
Landed weights were compiled by port for all species during the period. Ports with landings of >1,000 t are shown in Figure 2. Ports or regions with landings for a specific species >25% of the total landings of that species for all of Portugal, are shown in Figure 3. Annual species landings trends were further examined using a linear regression analysis (Table 1, Fig. 4-13).
[FIGURES 2-13 OMITTED]
Mean yearly price per kilogram (PPK) was calculated per species to examine changes in "demand" and the results of linear regression analysis...
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