Seasonal distribution of late larval and juvenile rockfish (Sebastes spp.) and associated environmental conditions off Oregon and Washington: new insights based on genetics

Abstract

Abstract-Surveys of juvenile and larval stages can be useful for management of commercially important marine fishes but require definitive species identification. From May through October 2005October -2008 trawls collected 78,407 late-larval and juvenile rockfish (Sebastes spp.) in shelf and slope waters off Oregon and Washington. Because of their small size and lack of pigmentation, we could identify only 4.1% (3266 individuals) of sampled rockfishes to species morphologically, representing a total of 17 species. An additional subsample (2534 individuals), representing 24 species and a 4-species complex, was identified by sequencing the mitochondrial cytochrome b gene and matching sequences to a reference data set. Incomplete overlap between identified species meant that a total of 29 species were identified overall. Community analyses showed that rockfish collected during the early upwelling season (May-June) were distinct from samples collected in the late upwelling season (July-October). Most rockfish were collected from outer-shelf or upper-slope stations, but distributions varied by month and year. Combining genetic and morphological identifications vastly improved our ability to assess seasonal distributions and abundances of planktonic rockfishes and is a step toward performing species-level surveys for this speciose and commercially important genus. Definitive identification based on visual and molecular methods as used here provides key information to enhance understanding of early-stage rockfish ecology.

Spatiotemporal patterns of variability in the abundance and distribution of winter-spawned pelagic juvenile rockfish in the California Current

“…The timing of rockfish recruitment is very seasonal, particularly for the more northerly winter spawning species, and the survey was originally designed to include the time of peak abundance levels of these species in Central California [ 14 ]. More recently, based on monthly trawl sampling with a different gear type [ 57 ] confirmed that in the waters off of Oregon and Washington, the May-June period was most important for the larger commercially important species (e.g., widow, canary, and yellowtail rockfishes) while the later summer was characterized by higher catches of forage species. Despite this general finding, interannual differences in parturition times and growth rates could shift the availability of some species within this sampling window [ 58 , 59 ].…”

Changes in kelp forest communities off Washington, USA, during and after the 2014-2016 marine heatwave and sea star wasting syndrome

“…Because it is difficult to visually distinguish many rockfish species when they are small, we categorized juvenile rockfishes into 5 groups established in the literature (Johansson et al 2018, Markel & Shurin 2020. ( 1) Yellowtail and black (YTB) included both yellowtail S. flavidus and black S. melanops rockfishes.…”

First observation of the use of coral habitat by larval northern rockfish (Sebastes polyspinis) in the western Gulf of Alaska

“…First, trawling for samples both destroys the habitat (Hourigan, 2009;Clark et al, 2016) and integrates catches over large distances, making fine-scale associations difficult to determine. Second, identification of the early life stages of rockfishes is difficult prior to development of distinguishing characteristics (Matarese et al, 1989;Johansson et al, 2018).…”