920 



Abstract.— We studied fine-scale ver- 

 tical distribution of northern anchovy, 

 EngrauliR mordax, eggs and larvae and 

 larvae of associated species at two sta- 

 tions off southern California in March- 

 April 1980 using a Manta ( neuston ) net 

 and a MESSHAI (multiple opening- 

 closing net I sampler. A pump and fluo- 

 rometry system was used to obtain chlo- 

 rophyll profiles. A storm with associ- 

 ated >feeavy seas interrupted sampling 

 for two days at the inshore station and 

 provided an opportunity to compare 

 pre- and poststorm egg and larval dis- 

 tribution and abundance. A total of 

 95,552 fish larvae were taken in the 

 MESSHAI (63 tows) and Manta nets 

 (41 tows), representing 49 taxa (genera 

 or species) in 27 families. Engraulis 

 mordax was the most abundant fish ( 95"f 

 of the total), followed by Leuroglossus 

 stilhius. Genyonemus lineatus, Steno- 

 brachius leucopsarus, Sebastes spp., 

 Seriphiis politus. Peprilus simillimus, 

 Paralichthys californicus, Citharichthys 

 spp., and Merluccius productus. Anchovy 

 eggs and larvae had a shallow distribu- 

 tion: 90'f of larvae and 95'7f of eggs were 

 found m the upper .30 m. Peak egg den- 

 sity was found in the neuston; peak lar- 

 val density, in the 10-20 m stratum. 

 Larvae of shallow-living shelf species 

 (G. lineatus, P. simiUimus.P.califoniicus) 

 typically occurred in the upper 20-30 m, 

 whereas larvae of predominantly deeper- 

 living demersal species (Sebastes spp., 

 M. productus I were found in the upper 

 80 m. Midwater species (L. stilbius. S. 

 leucopsarus) occurred at least to 200 m. 

 Anchovy eggs decreased in number af- 

 ter the storm. Anchovy larvae declined 

 even more sharply, despite an increase 

 in zooplankton and potential larval fish 

 prey, suggesting that starvation may 

 have resulted from disturbance of 

 microscale food patches. Alternatively, 

 larvae may have been advected away 

 from the site. Shallow-water shelf spe- 

 cies were rare at the inshore station 

 before the storm but appeared suddenly 

 afterwards as a result of seaward advec- 

 tion of shelf water by Ekman transport. 



Vertical distribution of eggs and larvae of 

 northern anchovy, Engraulis mordax, and 

 of the larvae of associated fishes at two sites 

 in the Southern California Bight 



H. Geoffrey Moser 



Southwest Fisheries Science Center 



PO Box 271 



La Jolla, California 92038 



E-mail address gmoseraiucsd edu 



Tilman Pommeranz 



Gotennng 66, D-53913 

 Swisttal, Odendorf 

 Germany 



Manuscript accepted 26 October 1998. 

 Fish Bull. 97: 920-943 ( 1999). 



The use of ichthyoplankton tech- 

 niques for estimating the biomass 

 of fish stocks has increased mark- 

 edly over the past two decades 

 (Hunter and Lo, 1993). Information 

 on the horizontal and vertical dis- 

 tribution of eggs or larvae of a tar- 

 get species is a requirement for 

 quantitative sampling of these 

 stages and for interpreting data 

 from integrated net tows and from 

 recently developed samplers such as 

 the continuous underway egg pump 

 (Checkley et al., 1997). The daily 

 egg production method ( DEPM ) was 

 developed at the Southwest Fisher- 

 ies Science Center to provide annual 

 biomass estimates needed to man- 

 age northern anchovy, Engraulis 

 mordax, an important coastal pe- 

 lagic species inhabiting the Califor- 

 nia Current region (Lasker, 1985). 

 During the development of this 

 method a cruise was conducted off 

 southern California that employed 

 a MESSHAI, a sampler with open- 

 ing-closing nets and environmental 

 sensors, to determine fine-scale ver- 

 tical distribution of eggs and larvae 

 of £. mordax (see preliminary data 

 in Pommeranz and Moser, 1987). 

 This information was needed to 

 supplement Ahlstrom's (1959) ver- 



tical distribution study based on 22 

 Leavett net tows taken on 9 cruises 

 over a 14-year period off southern 

 California and Baja California. The 

 MESSHAI study supplied informa- 

 tion on depth, ambient tempera- 

 ture, and diurnal periodicity of E. 

 mordax eggs needed to develop the 

 DEPM (Lasker, 1985). To compare 

 distributions at different bottom 

 depths, sampling was conducted at 

 two localities: an offshore site over 

 the Santa Catalina Basin and an 

 inshore site over the upper conti- 

 nental slope off Dana Point, Cali- 

 fornia. Anchovy larvae, the domi- 

 nant species in the MESSHAI 

 samples, were counted and mea- 

 sured for subsequent growth and 

 mortality studies. A storm inter- 

 rupted sampling at the inshore sta- 

 tion and provided an opportunity to 

 study the influence of water column 

 disturbance on the abundance and 

 depth distribution of eggs and lar- 

 vae of anchovy and associated spe- 

 cies. Mullin et al. (1985) described 

 the effects of this storm on the abun- 

 dance and vertical structure of phy- 

 toplankton, zooplankton, and total 

 fish larvae on the basis of pump 

 samples taken at the same time as 

 the MESSAI sampling at a locality 



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