Intra- and Inter-Annual Variation in Settlement of Larval Spotted Sand Bass Paralabrax maculatofasciatus within Mission Bay, California, in Relation to Oceanographic Conditions

It is widely acknowledged that estuaries serve as critical nurseries for a variety of juvenile fishes and invertebrates. Despite this, relatively little is known about settlement patterns of fishes in Southern California estuaries. Identifying factors that cause intra- and inter-annual variation in larval settlement success is critical to understanding future population fluctuations. In this study, we collected late-stage larvae of a recreationally important species, spotted sand bass (Paralabrax maculatofasciatus), as they entered the inlet of Mission Bay, San Diego, CA. Settlement stage fish were collected using 3 replicate monitoring units (tubes of plastic fencing filled with kelp and attached to the bottom with cinder blocks). Monitoring units were deployed and retrieved weekly with snorkeling gear from June-October in 2012, 2013, and 2014. Larvae were identified, counted, measured and weighed and otoliths were removed to determine individual characteristics of age, larval duration, and otolith growth rates. To determine factors that control weekly and annual patterns in settlement success, we compared abundance patterns to individual characteristics of the larvae and near shore oceanographic conditions such as water temperature, current strength and direction, and Chlorophyll levels. Identifying the mechanisms that control settlement success is an important step towards effective fisheries management.