appendix b final 2008 biological surveys of los angeles and long ...

3.0 Adult and Juvenile Fishes
No significant differences were found between total fish abundances during night sampling
(10,216) compared to day (10,102) (Table 3.4-1). Although more northern anchovy were
collected in day samples than in night samples, this pattern was opposite for most of the other
commonly collected demersal species such white croaker, queenfish, shiner surfperch, and
white surfperch, with higher numbers of those species being collected in night samples.
Mean fish abundance by station is presented in Table 3.4-2. The highest mean abundance (day
and night samples combined) occurred at outer harbor Stations LA7 (mean = 498) and Station
LA1 (mean = 367). The lowest mean abundances occurred at inner harbor Stations LA5 (mean
= 37) and Station LA6 (mean = 57). Mean abundance over all stations was 178 individuals, with
most station means (day and night combined) ranging between 100 and 200 (Table 3.4-2). As
in the case of total abundance, no statistical difference was found between day and night
samples for mean abundance.
Seasonal differences in trawl catch were not observed, and catches were highly variable over
the seasons. For example, day abundances decreased from winter to spring and then
increased to their highest levels in summer (July) (Figure 3.4-2). In contrast, night catches
increased from winter (January) to their highest levels in spring (April) and then decreased in
summer. Seasonal differences in trawl catch were observed during previous baseline surveys,
with summer having the highest abundances and winter typically having the lowest catches
(MEC 2002).
Additional otter trawl data, including raw data tables of abundance, biomass, and length
distributions are presented in Appendix C.
3.4.1.2 Biomass
A total of 837.3 kg of fish were collected during day and night surveys at all 19 stations
combined (Table 3.4-1). White croaker had the highest total biomass collected (317.9 kg),
representing 38% of the total trawl biomass. Other species with high total biomass included
California bat ray (Myliobatis californica) (21%), queenfish (10.6%), and California halibut (8.4%)
(Table 3.4-1).
In contrast to abundance, significant differences were found between day and night biomass,
with about twice as much total biomass being collected at night (561 kg) compared to day (276
kg) (Table 3.4-1). This was primarily due to large and highly variable night catches of northern
anchovy and queenfish, and a wide variety of other species that had higher night catches as
compared to day, such as California tonguefish (Symphurus atricauda), California lizardfish
(Synodus lucioceps), California scorpionfish (Scorpaena guttata), and shovelnose guitarfish
(Rhinobatos productus) (Table 3.4-1).
Mean fish biomass by station is presented in Table 3.4-2. The highest mean biomass (day and
night samples combined) was observed at outer harbor Station LA2 (mean = 17.8 kg) and inner
harbor Station LB12 (mean = 17.5 kg). The lowest mean biomass was reported at inner harbor
Station LA15 (mean = 2,072 g) and outer harbor Station LB6 (mean = 2.2 kg). Mean biomass at
most other stations was highly variable (Table 3.4-2). Mean biomass at night was statistically
higher (p