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

3.0 Adult and Juvenile Fishes
3.2.1 Pelagic (Lampara) Fishes
Pelagic species were sampled using a lampara
net, which generally extended from the surface
to mid water depths. One haul during the day
and one during the night was completed at
each station. The lampara net utilized for this
study included a 166 m corkline that was 22 m
deep, similar to previous harbor studies (e.g.,
MEC 2002). The net had two 67.7 m wings
with 15 cm mesh, a throat with 10 cm mesh,
and a 0.6 cm mesh bag. Lampara sampling
typically involves setting the net in a circle;
however, in some areas where boat movement
was restricted, the set was elliptical. As the net
is hauled in, the catch is driven into the back of
the net (bag end) where escape is unlikely. When hauls were sufficiently large, fish were
scooped from the bag end of the net using a standard bait brailer (diameter = 40 cm, depth = 50
cm) and placed into containers (buckets and bins) where the catch was sorted by species.
Small catches were transferred directly from the net into the sorting containers.
A maximum of six brailed scoops was processed, consistent with the previous baseline study
(MEC 2002). This approach helped avoid impractical processing time that would have been
associated with extremely large hauls and minimized incidental take from the sampling effort.
Consequently, if a haul appeared to be greater than six scoops, the fishes to be processed (six
scoops) were randomly withdrawn from the net. A count of the excess scoops returned to the
water was recorded for later use in calculating the total catch for the sample. This procedure
minimized the effects of being captured and significantly increased survival of most fishes.
All fishes were identified, measured (except in the case of abundant species – see below), and
weighed. Abundant species (>30 individuals) were subsampled by first randomly selecting 30
individuals of each species, measuring (standard length to the nearest mm) and weighing each
specimen (to 0.1 gm), then measuring the next 70 specimens (nearest 1 cm size class) and
recording an aggregate weight for these 70 individuals. Next, a total of 400 individuals was
counted and the aggregate weight determined along with the aggregate weight for any
remaining specimens. Fish abnormalities, including fin erosion, lesions, pop-eye, tumors, and
parasites were noted on pre-formatted data sheets set up for direct entry into the database.
Macroinvertebrates collected from lampara hauls were not recorded since they were not the
purpose of this sampling for pelagic fish.
3.2.2 Demersal and Epibenthic (Otter Trawl) Fishes
Demersal (bottom-oriented) fish and macroinvertebrates
were collected using a 7.6 m semi-balloon otter trawl
net constructed with 2.5 cm side mesh and fitted with a
1.3 cm mesh cod end that collects organisms as it is
towed along the seafloor. For each haul, the trawl was
towed at approximately 2 knots for 5 minutes,
corresponding to a sample area of about 300 m 2 . Trawl
catches were processed immediately on deck to
minimize fish mortality. Trawl-collected fish were
identified, measured, and weighed using the same
methods described above for pelagic fishes. Abundant
3–2 2008 Biological Surveys of Los Angeles and Long Beach Harbors
April 2010