RICHARDSON and PEARCY: COASTAL AND OCEANIC FISH LARVAE 



Comparison to the Northeast Pacific 



Direct comparisons between results from this 

 study and most previous reports on larval fishes in 

 the northeast Pacific with respect to species 

 composition, seasonality, and inshore-offshore 

 distribution patterns are difficult to make for 

 several reasons. Cruise tracks differed with re- 

 spect to distance of stations from shore and 

 proximity of stations to each other. Duration of 

 sampling effort and types of gear used were not the 

 same. Aron's (see footnote 4) data came from 

 mid-water trawl samples taken on long oceanic 

 cruise tracks between southern California and 

 southwest Alaska from July through October. 

 LeBrasseur's (see footnote 7) report was based on 

 mid-water trawl and NORPAC net collections 

 taken in the northeast Pacific at a broad array of 

 stations from 1956 to 1959. Waldron's (1972) 

 results, excluding Puget Sound, came from meter 

 net collections made in a grid pattern with 

 transects on each degree of latitude between 42° 

 and 51° (Oregon to British Columbia) and stations 

 extending from the 55-m isobath to 550 km 

 offshore. His samples covered only a 1-mo period 

 in April and May. Naplin et al. (see footnote 8) 

 reported on samples collected with 60-cm bongos 

 along three widely spaced transects off 

 Washington and British Columbia in October and 

 November. Richardson's (1973) data came from 

 70-cm bongo, meter net, and mid-water trawl 

 samples collected off Oregon at a wide array of 

 stations from May to October. However, some 

 trends are evident. 



The most abundant, most dominant, and most 

 frequently taken taxa in the above mentioned 

 studies (which included few or no samples from 

 nearshore areas) were myctophids, mainly 

 Stenobrachius leucopsarus, Tarletonbeania 

 crenularis, and sometimes Protomyctophum 

 thompsoni (andDiaphus theta in southern areas), 

 and scorpaenids, mainly Sebastes spp. (particu- 

 larly over shelf and slope areas). This is similar to 

 the offshore assemblage in this study. Richardson 

 (1973) also found Engraulis mordax to be im- 

 portant as it was in our offshore assemblage. 

 Those studies which included samples from shelf 

 areas showed increased importance of pleuronec- 

 tid larvae, e.g., Isopsetta isolepis, Parophrys 

 vetulus, Platichthys stellatus, and Psettichthys 

 melanostictus (Waldron 1972). None of the above 

 studies included intensive sampling in the 

 nearshore zone (e.g., within 9 km of the coast) to 



allow detailed comparison with our coastal 

 assemblage. However, Aron (1959) stated that 

 large numbers ofcapelin,Ma//otas uillosus, larvae 

 were taken in northerly inshore waters. Also, 

 osmerids and Ammodytes hexapterus were among 

 the 10 most abundant larvae taken in Waldron's 

 (1972) samples. Richardson (1973) showed that 

 osmerid larvae were taken in moderate numbers 

 at nearshore stations although they were not top 

 dominants when all samples were combined. More 

 recent samples from 12 transects 2 to 56 km off 

 Oregon (Laroche and Richardson 16 ) have shown 

 that osmerids, Parophrys vetulus, I. isolepis, 

 Microgadus proximus, and some cottids are 

 dominant in the coastal waters from the Columbia 

 River to Cape Blanco in spring months, which is 

 similar to our coastal assemblage. 



The only available information on seasonality 

 based on one or more years of data was presented 

 by LeBrasseur (see footnote 7). The greatest 

 number of larvae per sample (1.0) was taken in the 

 March-May quarter, with 0.3 in June- August, 0.1 

 in September-November, and 0.05 in December- 

 February. The May-October data discussed by 

 Richardson (1973) showed an abundance peak in 

 May in 1-m net samples and a peak in July- August 

 in bongo and mid-water trawl samples with low 

 abundances after August. The data of Naplin et al. 

 (see footnote 9) showed low abundances (except for 

 myctophids) and low numbers of species in 

 October-November. These trends are similar to 

 those found in this study. 



No previous studies have demonstrated actual 

 coastal and offshore assemblages of fish larvae 

 although mention has been made of a break in 

 species composition, abundance, and frequency of 

 occurrence between shelf and oceanic areas. Aron 

 (1959) stated that, in oceanic regions, the larvae of 

 inshore fishes disappeared and myctophid larvae 

 became common. LeBrasseur (see footnote 7) 

 indicated larvae were taken in 5% of the samples 

 within 100 miles of the coast but in only 1% of the 

 samples from farther offshore. Waldron (1972) 

 reported a greater number of larvae were taken 

 inside the 914-m isobath than beyond it. More 

 recent data (Laroche and Richardson see footnote 

 16) have shown that coastal and offshore as- 

 semblages offish larvae, similar to those described 

 in this paper for the mid-Oregon coast, occur along 



16 Laroche, J. L., and S. L. Richardson. Spring patterns of larval 

 fish distributions from the Columbia River to Cape Blanco, 

 Oregon, 1972-1975, with emphasis on English sole, Parophrys 

 vetulus. Manuscr. 



143 



