Life History & Otolith Studies
Current research and past publications
Morphometric Relationships of Marine Fishes Common to Central California and the Southern California Bight
Chelsea M. Williams, Jonathan P. Williams, Jeremy T. Claisse, Daniel J. Pondella II., Michael L. Domeier, and Laurel A. Zahn
Length-weight relationships have several applications in fish stock assessments and ecological studies (e.g., Ricker 1975, Newman et al. 2006). Particularly, they are important for visual surveys of fish populations where the estimated total lengths are converted to weights to estimate fish biomass (e.g., Hamilton et al. 2010, Sala et al. 2012). The available information on length-weight relationships and length-length conversions for marine fishes in California are mostly limited to commercial catch (RecFIN 2009) or the occasional ecological survey (Miller et al. 2008), and a recent compilation of these parameters (Cailliet et al. 2000) demonstrated many species are lacking this basic information. Fishes used in this study were collected in various large- and small-scale projects by the Vantuna Research Group, Occidental College and California State University Northridge from 1984 to 2012. These included state-mandated programs dedicated to assessing the biological and economic impacts of its stocking efforts (OHREP) and localized fisheries surveys (San Diego and Morro Bay) where a variety of species were caught. Measurements of lengths and individual weights provide the opportunity to generate the additional information on morphometric relationships that will be useful to other researchers. Here we provide length-weight equation parameters for 71 near-shore marine fish species, common to central and southern California (Miller and Lea 1972) (57 from Class Actinopterygii and 14 from Subclass Elasmobranchii) and standard length (SL) to total length (TL) conversions for 32 species (Class Actinopterygii).
Patterns of Life History and Habitat Use of an Important Recreational Fishery Species, Spotfin Croaker, and Their Potential Fishery Implications
Jonathan P. Williamsa, Jeremy T. Claissea, Daniel J. Pondella IIa, Lea Medeirosb, Charles F. Vallec, and Michael A. Shane
Spotfin croakers Roncador stearnsii, a prized recreational catch, were collected throughout the Southern California Bight, primarily as bycatch from a long-term, scientific gill-net collection effort. The maximum otolith-based age in the present study was 24 years—14 years greater than in a previous scale-based aging study. Multiple models were used to estimate mean length at age, including models that utilize larvae as well as juveniles and adults, and the model selection results suggest sexual dimorphism in growth patterns. The juvenile and adult catch per unit effort reflected a clear pattern of habitat selectivity, with fish strongly preferring soft-bottom habitats. Catches in rocky-reef areas were limited but tended to increase with water temperature. The data also suggest that spotfin croakers segregate themselves sexually during the spawning season, when recreational fishing from jetties will target males and fish caught in bays and estuaries are more likely to be spawning females. These results provide further evidence for the importance of protection and restoration efforts for estuaries and bays along this well-developed coastline. The growth of larvae captured in plankton tows in July and September 2004 was substantially faster than that of larvae sampled in May, which coincided with warmer sea surface temperatures, highlighting a potentially important relationship relating temperature (and therefore geography) and settlement success.
New record of Pacific sierra (Scomberomorus sierra) with notes on previous California records
Jonathan P. Williams, Daniel J. Pondella II, Brent M. Haggin, and Larry G. Allen
On 22 October 2006, a Pacific sierra (Scomberomorus sierra) (Figure 1) was caught by gillnet near Mother’s Beach, Marina del Rey, Los Angeles County, California (33º58’50”N, 118º27’25”W) during sampling for juvenile white seabass (Atractoscion nobilis) (as described in Allen et al. 2007). This catch represents the northernmost record of Pacific sierra, and one of several specimens known from California. The net was set perpendicular to shore the previous evening (21 October 2006) approximately 1.4 hours before sunset at 1650 PDT in 20.2º C water and at a depth of 3.4 m. The net was retrieved at 0933 PDT, approximately 2.5 hours after sunrise and four minutes after a 1.76-m high tide. A new moon occurred the previous evening at 2214 PDT and helped produce a 1.26-m flooding tidal swing overnight.
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