(1 - 3 of 3)
- Changes in size composition and relative abundance of fishes in Central California after a decade of spatial fishing closures
- Rockfish Conservation Areas (RCAs) were implemented in 2000 to 2003 along the West Coast of the United States to reduce fishing mortality on rockfish (Sebastes spp.) and other groundfish species that had recently been declared overfished. In 2012, we initiated a study to compare recent catch rates, species compositions and length frequencies of fishes inside and outside the RCAs with data collected in central California between 1995 and 1998. At all sites surveyed, total catch rates from the new surveys (2012–14) were significantly higher than catch rates from before RCA implementation (1995–98). The majority of the differences were due to the increased relative abundance of yellowtail rockfish (Sebastes flavidus), although other species, including the overfished canary rockfish (Sebastes pinniger), also increased. Differences in the size composition of species between the two time periods reflected both the increased survival of older fishes and higher recruitment success in the past decade. © 2015, Scripps Institution of Oceanography. All rights reserved., published
- Marks, Fields, Starr, Field, Miller, Beyer, Sogard, Wilson-Vandenberg, Howard
- Ontogeny of critical swimming speeds for larval and pelagic juvenile rockfishes (Sebastes spp., family Scorpaenidae)
- Understanding the mechanisms that affect larval dispersal is critical to management of marine populations. Rockfishes Sebastes spp. do not settle to benthic habitats immediately after metamorphosis, but instead remain in the water column for weeks to months. Movements of larvae and pelagic juveniles during their months at sea are largely unknown. It is traditionally thought that young rockfishes are planktonic, moving at the mercy of ocean currents, but this assumption is unverified. In this study, swimming capabilities (critical speed) of larval and pelagic juvenile stages of 6 rockfish species (blue [S. mystinus], yellowtail [S. flavidus], brown [S. auriculatus], kelp [S. atrovirens], gopher [S. carnatus], and splitnose [S. diploproa]) were evaluated to determine their ability to behaviorally influence dispersal. Rockfish larvae have critical speeds of 0.5 to 1.8 cm s-1 (1 to 3 body lengths per second [bl s-1]) at parturition, whereas newly settled juveniles are capable of swimming 8.6 to 53.5 cm s-1 (5 to 9 bl s-1). Swimming ability increases throughout ontogeny and postflexion rockfishes can swim faster than typical water motions in their natural habitat (i.e. mean ocean currents off central California). Critical speeds for Sebastes spp. are substantially lower than those for larvae and juveniles of tropical species at similar body sizes. Rockfishes, however, have swimming speeds at settlement comparable to some tropical species, as rockfishes settle at larger sizes. The increasing ability of rockfishes to outswim currents during their pelagic phase (acting as nekton rather than plankton) may promote individual survival as well as enhance retention and/or long-distance dispersal-thus swimming has important implications for population connectivity and sustainability. © Inter-Research 2014.
- Kashef, Sogard, Fisher, Largier