Demographic Parameters of Yellowfin Croaker, Umbrina roncador (Perciformes: Sciaenidae), from the Southern California Bight¹

Abstract

The yellowfin croaker, Umbrina roncador Jordan & Gilbert, 1882, is a common nearshore and surf-zone species in the southern California bight. Age was determined for individuals (n ¼ 1,209) using annual increments in otoliths, and size at age was modeled using the von Bertalanffy growth curve (L . Age and growth modeling based upon otolith length (OL) and width (OW ) measurements were assessed and were consistent with body measurements. Males and females were found in all size classes and in an overall 51 : 49 ratio that was not significantly different from a 50% sex ratio, suggesting that these fish are gonochores. Fish were reproductive during summer months, with gonadosomatic indices (females, 5.65%; males, 5.51%) consistent with group-spawning fishes. Data from two separate monitoring programs indicated that yellowfin croaker catch-per-unit-effort (CPUE) fluctuated appreciably from 1992 to 2006 on both spatial and temporal scales. CPUE also declined significantly in the latter years of these programs. Based on samples collected between 2003 and 2004, an estimate of overall annual total mortality was A ¼ 0:4492, and instantaneous coefficient of total mortality was estimated at Z ¼ 0:5964. Recruitment year classes were back calculated using annual survivorship. Year class strength was variable and declined significantly by the end of this study. Considering the high temporal and spatial variation in estimates of abundance and recruitment, coupled with the likelihood that these fish employ a probable group-spawning reproductive behavior, we recommend a cautious approach for the future management of this species.

An empirical test of the ‘shark nursery area concept’ in Texas bays using a long-term fisheries-independent data set

“…Prior to analyses, shark CPUE data from the 45 nets season -1 bay -1 were aggregated into a single mean value per season per bay. Seasonal data were subsequently aggregated into an annual mean value per bay system to stabilize variance and to remove excess zeros from the matrix (Pondella et al 2008). Upper Laguna Madre was excluded from the analysis as no bull sharks were captured in this bay during the 30 yr study.…”

Habitat type and environmental conditions influence the age and growth of a temperate marine damselfish

“…Sexual dimorphism in size was observed within all populations of Garibaldi and agreed with Clarke's (1970) observation that males achieve larger body size than females. This appears to be an unusual trait for damselfish species (Dulcǐcá nd Kraljevic, 1995;Kim et al, 2016) and nearshore dioicous reef-associated fish in southern California (Love and Westphal, 1981; Love et al, 1987;MacNair et al, 2001;Laidig et al, 2003;Pondella et al, 2008;Grebel and Cailliet, 2010;Williams et al, 2012;Miller et al, 2014), where adult females are typically larger. Only one other damselfish species, the Canary Damsel (Similiparma lurida) from the northeastern Atlantic (Garcıá-Mederos et al, 2016), shows the same pattern of males growing larger than females.…”