Artisanal and industrial fisheries in Argentina: Comparative effects of the activity on an important commercial sciaenid

LÓPEZ CAZORLA A. C.; RUARTE C.; MOLINA J. M.; HOZBOR N.

Edimburgo

Congreso; 6th World Fisheries Congress; 2012

World Council of Fisheries Societies

The striped weakfish, Cynoscion guatucupa Cuvier 1829, is a commercially important sciaenid found in estuarine, coastal and marine waters of Argentina, Uruguay and Brazil. The homogenous coastal (from the coast to 50 m depth) zone of south Buenos Aires province, Argentina, comprises the El Rincón area (ERA) (39 ? 41° S) and Bahía Blanca estuary (BBE), which is located in the coastal region of the mentioned area. Cynoscion guatucupa has been captured by artisanal fishermen in this estuary since the 1950?s. During the period 1972 - 1982 catches of this species varied between 45% and 70% of the total annual catch; however at the end of 1990s these percentages dropped to 15%. Populations of Argentinean hake (Merluccius hubbsi) have been intensely fished by the industrial fleet of Argentina. In the period 1987-1998, effort applied to the capture of this species has increased sharply, yielding landings that triplicate the maximum values of previous years. Population biomass started decreasing in the same fashion, with a sharp decrease from 1986 to 1989 (with half the biomass reduced), and another, more pronounced decrease, from 1991 to 1999 (again, almost half of the total biomass was lost). In 1997 a fishing closure was implemented when M. hubbsi juveniles stock dropped dangerously. Part of the fleet kept fishing M. hubbsi around the closed area, but an important fraction of these ships started operating in ERA, targeting other species of less commercial value, such as C. guatucupa. We hypothesize that the observed decrease on C. guatucupa stocks in BBE, is a consequence of the increase in the industrial fisheries activity in ERA. In order to test this hypothesis, our objectives were to describe the artisanal fleet operating in BBE (Fishing gear, ships, fishing effort, etc), and compare the results of catch per unit effort estimated for the period 1992-2009 of the industrial fisheries operating in ERA with the artisanal fisheries operating in BBE. Catch (C) and effort (f) data were obtained from the landing records of the Dirección Nacional de Pesca y Acuicultura, the national entity of Argentina that regulates and manages fishing and agricultural activities. Capture per unit effort (CPUE) was calculated for both areas and the studied period as CPUE= C/f. Polynomial models were fitted to total catch, effort and CPUE data from ERA and BBE, in order to assess the possible variations between them. Models where then compared with an ANOVA to test the significance of variations. We found significant differences between the reported landings for ERA and for BBE with second and third order polynomial models (P70%). This result suggests that as catches in ERA increase, catches in BBE decrease. Effort showed significant fit with the third order polynomial model (P60%). From 1992 to 1997, effort applied on ERA increased as effort on BBE decreased, but from 1998 the effort dropped considerably in both regions, probably due to scarce yields up to 2003. Since 2004 closures were implemented in the ERA, forcing an even greater drop in fishing effort. A slight recovery in the fishing effort of BBE is shown, starting in 2004. Of the models used for CPUE, third order polynomial model showed a significant fit (P60%). Synchronically, as shown for total landings, CPUE in BBE decreased, as it increased in ERA. Our results suggest that the artisanal fishery of C. guatucupa in BBE is affected by increasing fishing pressure by the industrial fleet on ERA.