Abstract
Dolphinfish, Coryphaena hippurus, is a widely distributed epipelagic species that migrates seasonally in different areas of the oceans. In Venezuelan and adjacent waters it is fished commercially mainly by artisanal fishermen using surface longline and gillnet. Information on effort, location, catch at size, weight and sex determination from 1991 to 1997 was used to determine the seasonality of the demographic structure of dolphinfish off Venezuela. A total of 4876 specimens were measured and sexed from port sampling and observer-covered trips in longline vessels. Oocyte development and spawning season were estimated from samples collected in observer-covered trips on board longline vessels. The seasonality of dolphinfish off Venezuela appears to show two different size groups: one arriving at the end of the first quarter comprised of large mature individuals that will spawn in May, and one arriving at the beginning of the third quarter comprised of smaller specimens that will spawn in October-November. Sex ratio at size was significantly biased towards females in all quarters for smaller specimens (120 cm FL). Oocyte development revealed an indeterminate spawning pattern, as shown by the asynchronous oocyte development in the material examined. A reproductive strategy is proposed based on the seasonal movement pattern of dolphinfish off Venezuela, which is used to ensure recruitment success due to the prevailing environmental conditions off the Venezuelan coasts.
Highlights
Dolphinfish, Coryphaena hippurus L., 1758, is a mid-size, fast-swimming, epipelagic oceanic species that migrates seasonally in different areas of the oceans and is widely distributed throughout the tropical, subtropical and temperate oceans between40°N and 40°S (Palko et al, 1982)
In late 1980, the demand for, and economic importance of, this species began to grow, inducing the artisanal fleets to start targetting dolphinfish. This situation became more evident in the northeastern region, where most of the artisanal surface longline fleet is based, which shifted fishing operations to target dolphinfish during the season of higher relative abundance (Marcano et al, 1997)
Sex ratio at size was estimated based on 3469 females (20-160 cm FL) and 1407 males (40-170 cm FL) caught in Venezuelan and adjacent waters
Summary
Dolphinfish, Coryphaena hippurus L., 1758, is a mid-size, fast-swimming, epipelagic oceanic species that migrates seasonally in different areas of the oceans and is widely distributed throughout the tropical, subtropical and temperate oceans between40°N and 40°S (Palko et al, 1982). In late 1980, the demand for, and economic importance of, this species began to grow, inducing the artisanal fleets to start targetting dolphinfish This situation became more evident in the northeastern region, where most of the artisanal surface longline fleet is based, which shifted fishing operations to target dolphinfish during the season of higher relative abundance (Marcano et al, 1997). At present, it is one of the most important large pelagic fish landed by the artisanal fishermen in terms of weight and revenue
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