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Torres-Irineo E.,IRD Montpellier | Torres-Irineo E.,National Autonomous University of Mexico | Dreyfus-Leon M.,Instituto Nacional Of La Pesca | Gaertner D.,IRD Montpellier | And 2 more authors.
Ambio | Year: 2016

The failure to achieve fisheries management objectives has been broadly discussed in international meetings. Measuring the effects of fishery regulations is difficult due to the lack of detailed information. The yellowfin tuna fishery in the eastern Pacific Ocean offers an opportunity to evaluate the fishers’ responses to temporal regulations. We used data from observers on-board Mexican purse-seine fleet, which is the main fleet fishing on dolphin-associated tuna schools. In 2002, the Inter-American Tropical Tuna Commission implementeda closed season to reduce fishing effort for this fishery. For the period 1992–2008, we analysed three fishery indicators using generalized estimating equations to evaluate the fishers’ response to the closure. We found that purse-seiners decreased their time spent in port, increased their fishing sets, and maintained their proportion of successful fishing sets. Our results highlight the relevance of accounting for the fisher behaviour to understand fisheries dynamics when establishing management regulations. © 2016 Royal Swedish Academy of Sciences

Ruiz-Campos G.,Autonomous University of Baja California | Castro-Aguirre J.L.,National Polytechnic Institute of Mexico | Velez-Marin R.,Instituto Nacional Of La Pesca
Revista Mexicana de Biodiversidad | Year: 2010

New specimens and new records of occurrence for 10 species of chondrichthyan (elasmobranch and chimaeroid) fishes previously unknown or little documented for the continental shelf of the Mexican Pacific are reported. This contribution provides the fi rst record of Centroscyllium nigrum, Isurus paucus, and Bathyraja trachura for the Mexican Pacific, as well as new specimens of Hydrolagus colliei, Hexanchus griseus, Echinorhinus cookei, Pseudocarcharias kamoharai, and Raja velezi for the western coast of the Baja California Peninsula, including the intermediate record within the known distribution range for Apristurus kampae, and the southernmost record for Raja inornata.

Lopez-Gonzalez L.C.,Instituto Nacional Of La Pesca | Sanchez-Gutierrez F.J.,National Polytechnic Institute of Mexico
Latin American Journal of Aquatic Research | Year: 2011

The fish assemblage in a coastal lagoon with mangroves known as "Rancho Bueno" was determined and associated with environmental parameters. We used an experimental otter trawl net to catch the fish, and 62 fish species were identified from 48 genera and 30 families. The most abundant species were: Etropus crossotus, Eucinostomus gracilis, Paralabrax maculatofasciatus, Sphoeroides annulatus, and Eucinostomus dowii. The water temperature changed seasonally, being warm from July through December and cold from January through June. We found more fish species during the warm season than during the cold season. The southern area of the coastal lagoon had the highest diversity and species richness. The small size of the fishes registered confirms the ecological role of coastal lagoons as nursery areas that offer protection and feeding to commercially important fish near Bahía Magdalena, Mexico.

Torres-Irineo E.,Montpellier University | Gaertner D.,Montpellier University | Chassot E.,IRD Montpellier | Dreyfus-Leon M.,Instituto Nacional Of La Pesca
Fisheries Research | Year: 2014

Technological advancements can influence both the fishing power of a fleet and the fishing strategies it employs. To investigate these potential linkages, we examined almost three decades of data (1981-2008) from French tropical tuna purse seiners operating in the eastern Atlantic Ocean. Applying a sequence of statistical methods at different temporal and spatial scales, we analyzed two indicators of fishing power (sets per boat-day on fish aggregating devices (FADs) and sets per boat-day on free-swimming schools) each of which represent a distinct fishing mode. Our results show that the increasing modernization of this fleet has led to increases in both fishing power and the available number of fishing strategies to choose from. A key output of this analysis was the breakdown of fishing power time series (for each fishing mode) into separate periods of continuous years during which catchability was assumed to be constant, thus identifying regime shifts. This partitioning allowed us to identify when key changes occurred in the fishery. Changes in FAD-associated fishing were mostly driven by the introduction of radio beacons (early 1990s) which lead to an increase in fishing effort and an expansion of fishing grounds (direct effect) and the implementation of time-area management measures which resulted in a fragmentation of the traditional fishing grounds in the 2000s (indirect effect). During the same period, fishing on free-swimming schools also increased despite the biomass of stocks decreasing and fishing grounds remaining unchanged. This suggests these increases were driven by improvements in fish detection technology (e.g., bird radars, sonar). These identified increases are not entirely unexpected: indeed it is widely recognized that fishing power in the purse seine tuna fishery has increased over time. However, these increases do not necessarily occur linearly. Thus, understanding how fishing power is changing over time (such as determining when regime shifts occur) is critical to improving the CPUE standardization procedure in tropical tuna purse seine fisheries. © 2014 Elsevier B.V.

Pacheco-Ruiz I.,Autonomous University of Baja California | Cabello-Pasini A.,Autonomous University of Baja California | Zertuche-Gonzalez J.A.,Autonomous University of Baja California | Murray S.,California State University, Fullerton | And 3 more authors.
Botanica Marina | Year: 2011

We tested effects of light and temperature on survival and development of spores of Chondracanthus squarrulosus to determine their influence on the in situ haploid: diploid population ratio. Initially, reproductive tissues of both phases were induced to release spores under standard laboratory conditions. As in most of the Gigartinales, larger numbers of carpospores were released relative to tetraspores (4:1). Tetraspores, however, had higher germination rates (70% vs. 30%). Gametophytes and tetrasporophytes, germinated from spores, were exposed to light and temperature gradients (45-135 μmol photons m -2 s-1 and 14-30°C). Tetrasporophyte survivorship was negatively affected by high temperatures. In contrast, gametophytes had 100% survival at all temperatures tested and their growth rates were greater than those observed in the tetrasporophytes, particularly at higher temperatures. Therefore, the low germination rate of carpospores and the greater survivorship in the first gametophyte stages at higher temperatures would help explain the dominance of the gametophytes over tetrasporophytes of C. squarrulosus in the Gulf of California. A Leslie matrix based on the number of spores released and adult plant survival demonstrated that it is possible to generate a stable adult plant ratio close to the one that we observed in the field. © 2011 by Walter de Gruyter Berlin New York.

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