Pesca con anzuelos en barcos palangreros del Océano Pacífico mexicano: efectos en la captura y peso de tiburones y otras especies

Revista de biología marina y oceanografía, ISSN 0717-3326, Vol. 44, Nº. 1, 2009, pags. 163-172 04/2009; 44(1). DOI: 10.4067/S0718-19572009000100016
Source: OAI


We analyzed the effects of two hook types and two bait types on the catch rate of long liners from the northwest Pacific Ocean off Mexico. In 47 sets, from four commercial fishing trips done during March 2005 to August 2006, we used conventional J-style 9/0 11º offset hooks and experimental circle 16/0 0º offset hooks. We used two bait types: jumbo squid (Dosidicus gigas) and striped mullet juveniles (Mugil cephalus). A factorial experiment split-plot design was applied. A total of 1304 organisms were caught, where 86.5% were sharks, and blue shark (Prionace glauca) was the dominant specie and 13.5% from other species. While the hook type did not affect significantly the catch rate and weight of sharks and other species, the bait type had a significant effect, mainly on the catch rate of blue shark, silky shark (Carcharhinus falciformis), dolphinfish (Coryphaena hippurus), and the weight of total catch. The Tukey test showed that the mean catch rate of blue shark, silky shark, dolphinfish, total catch and weight were higher for squid bait than for striped mullet Resumen.- Se evaluó el efecto de dos tipos de anzuelos y dos tipos de carnada en la tasa de captura de barcos palangreros en el noroeste del Océano Pacífico mexicano. Se realizaron cuatro viajes de pesca comercial con un total de 47 lances, entre marzo de 2005 y agosto de 2006. Los dos tipos de anzuelos usados fueron: recto 11º de inclinado 9/0 de uso tradicional y circular plano 16/0 (experimental). Se utilizaron dos tipos de carnada: calamar gigante (Dosidicus gigas) y peces juveniles de lisa (Mugil cephalus). Se aplicó un diseño experimental factorial en parcelas divididas (�split-split-plot�). Se capturó un total de 1304 ejemplares, de los cuales 86,5% fueron tiburones, siendo el tiburón azul (Prionace glauca) la especie dominante y 13,5% estuvo constituido por otras especies. Los resultados mostraron que el tipo de anzuelo no presentó diferencias significativas en la tasa y peso de la captura de tiburones y de las otras especies consideradas como pesca incidental; el tipo de carnada presentó un efecto significativo en la tasa de captura, principalmente en tiburón azul, tiburón jaquetón (Carcharhinus falciformis), dorado (Coryphaena hippurus), así como en el peso de la captura total. La prueba de Tukey, mostró que la carnada de calamar presentó una media superior a la carnada de lisa en la tasa de captura del tiburón azul, piloto, dorado, captura y peso total.

Full-text preview

Available from:
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Circle hooks have gained recent attention as a cost-effective bycatch mitigation tool in pelagic longline fisheries, particularly for marine turtles. Over the last few years, a growing number of studies have investigated the use of circle hooks and their effects on other species, including elasmobranchs. To elucidate the potential value of circle hook use as a tool for shark conservation and management in pelagic longline fisheries, we conducted a quantitative review of all available studies to date. We compiled 15 published and eight gray literature studies and where possible used random effects meta-analysis and analysis of covariance to test the effects of circle hooks on catchability and at-vessel mortality rates. Overall, results suggest that using circle hooks on pelagic longlines do not have a major effect on shark catch rates, but do reduce at-vessel mortality compared to J-hooks. Thus circle hooks should be seen as one potential tool to help reduce bycatch mortality of sharks in longline fisheries. However, the high level of heterogeneity found between studies highlights the need for shark-specific controlled experiments to provide more definitive results.
    Full-text · Article · Jul 2012 · Bulletin of Marine Science -Miami-
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Adequate conservation and management of shark populations is becoming increasingly important on a global scale, especially because many species are exceptionally vulnerable to overfishing. Yet, reported catch statistics for sharks are incomplete, and mortality estimates have not been available for sharks as a group. Here, the global catch and mortality of sharks from reported and unreported landings, discards, and shark finning are being estimated at 1.44 million metric tons for the year 2000, and at only slightly less in 2010 (1.41 million tons). Based on an analysis of average shark weights, this translates into a total annual mortality estimate of about 100 million sharks in 2000, and about 97 million sharks in 2010, with a total range of possible values between 63 and 273 million sharks per year. Further, the exploitation rate for sharks as a group was calculated by dividing two independent mortality estimates by an estimate of total global biomass. As an alternative approach, exploitation rates for individual shark populations were compiled and averaged from stock assessments and other published sources. The resulting three independent estimates of the average exploitation rate ranged between 6.4% and 7.9% of sharks killed per year. This exceeds the average rebound rate for many shark populations, estimated from the life history information on 62 shark species (rebound rates averaged 4.9% per year), and explains the ongoing declines in most populations for which data exist. The consequences of these unsustainable catch and mortality rates for marine ecosystems could be substantial. Global total shark mortality, therefore, needs to be reduced drastically in order to rebuild depleted populations and restore marine ecosystems with functional top predators.
    Full-text · Article · Jul 2013 · Marine Policy
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Populations of hammerhead sharks (Sphyrna and Eusphyra) have declined in many regions of the world. Six of the eight hammerheads known to date are distributed in the Mexican Pacific: S. corona, S. lewini, S. media, S. mokarran, S. tiburo and S. zygaena. These species, with exception of S. corona, were abundant in the Gulf of California in 1960s. I analyze records from fishery-dependent and fishery-independent surveys, and records from ichthyological collections to determine the presence and frequency of hammerheads in the Mexican Pacific. The most frequent hammerheads in fishery-dependent and fishery-independent surveys were S. lewini and S. zygaena. It appears that S. media, S. mokarran and S. tiburo might have been extirpated from the Gulf of California. In the last two decades, records of S. mokarran (n = 61) were restricted to Central and Southern Mexican Pacific, and records of S. tiburo (n = 3) and S. media (n = 3) were restricted to the Southern region. Given the continued fishing pressure, inferred declines and the probable extirpation of populations, S. tiburo and S. media should be reassessed for the IUCN red list as Endangered or Critically Endangered. Sphyrna corona should be reassessed as Endangered or Critically Endangered, because it is endemic to the Eastern Pacific and recent records have been obtained only from Colombian waters. The Endangered status of S. mokarran is confirmed for this region.
    Full-text · Article · Apr 2014 · Reviews in Fish Biology and Fisheries