Abstract
The first steps have been taken to analyze the effects of small pelagic harvests on the Gulf of California ecosystem. The primary goal of this study was to estimate the latitudinal differences in regionalized baselines of endangered and threatened marine species attracted to a purse seine in a Mexican fishery of small pelagic fish. We also analyzed the spatial patterns in fishing effort in the Gulf of California. Seven zones were analyzed in the Gulf of California, including the east and west coasts, and a total of 3,051 fishing sets were analyzed during January 2013 and July 2014; the data provided a comprehensive picture of the distribution of the fishing effort, small pelagic fishes harvested, and the presence of species attracted to the fishing sets. The region in the upper Gulf of California showed a low presence of individuals, and the east coast recorded more sightings than the west coast; consequently the fishing effort was mainly distributed in the east coast. The number of individuals for several species sighted and counted by fishing set was used for each zone in the Gulf of California, and a conservative baseline based on the Pennington estimator was computed. It provided an average value of endangered and threatened marine species attracted to a purse seine for each zone. The Pennington estimator is recommended due to the precision of the confidence intervals and the nature of the uncertainty in the data collection based on sightings.
Highlights
A different spatial pattern was observed for the fishing effort during 2014, Zone III remained a suitable region for harvest, and Zones IV and V showed a concentration of fishing sets greater that observed in Zone III (Figure 4)
The fishing effort during 2013 was concentrated on the central east coast of the Gulf of California, and during 2014 the fishing effort changed its location toward southern coasts, identifying a more extended region where the fishing sets were recorded, and even the boundary between Zones II and III were suitable for harvest
Specific studies are required to analyze the effect of the bycatch on the sardine fishery in the Gulf of California, the results suggest that the fishing gear used to catch small pelagic species has little impact on the ecosystem; the incidental catch is low, and even negligible for some taxonomic groups, such as birds, sharks, fishes, and reptiles
Summary
The first Pacific sardine fishery (Sardinops sagax) in Mexico was established in the port of Ensenada, Baja California, in the late 1920s, and there were significant records of catches there since the late 1940s, as well as later in Isla Cedros, Baja California, and Bahía Magdalena, Baja California Sur (Pedrín and Ancheita, 1976; Lluch-Belda et al, 1986; Cisneros-Mata et al, 1995; Nevárez-Martínez et al, 2014). The discovery of a significant stock of Pacific sardine and other small pelagic species in the Gulf of California, this fishing activity moved to the Gulf in the late 1960s, becoming the basis for what is a small pelagic fishery whose base ports are in Guaymas and Yavaros, Sonora These ports are extensively developed, with important fleets and the most significant industrial plant in the country (Cisneros-Mata et al, 1995; Nevárez-Martínez et al, 2014). Larger animals, such as marlin or dolphins, can usually be released alive by lowering a section of the net or using a dip net, and birds are kept out of the fishing gear using a jet of water and by making a lot of noise
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