2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...
2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...
2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...
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<strong>Bolsa</strong> <strong>Chica</strong> Lowlands Restoration <strong>Monitoring</strong><br />
<strong>2008</strong> <strong>Annual</strong> <strong>Report</strong><br />
The otter trawl consists of a 4.6-m trawl with 2-cm mesh in the body and 0.3-cm mesh in the cod end.<br />
The otter trawl was deployed at offshore sampling locations using a small vessel traveling between 1.5<br />
and 2 knots along 250-m transects. The trawl was used to sample primarily demersal offshore fish at<br />
Stations 1 and 2 in the FTB. The otter trawl was not used in the MPM due to the inaccessibility of the<br />
site by boat.<br />
The purse seine consists of a 66-m x 6-m seine with 1.2-cm mesh<br />
in the wings and 0.6-cm mesh in the bag. The purse seine was<br />
deployed at offshore sampling locations using a small vessel.<br />
This gear was used to sample adult and juvenile fish species in the<br />
water column as well as demersal fish at Stations 1 and 2 in the<br />
FTB. The purse seine was not used in the MPM due to the<br />
inaccessibility of the site by boat.<br />
Purse seine being deployed in the FTB.<br />
The large beach seine consists of a 15- m x 1.8-m net with a 1.8-m x 1.8-m x 1.8-m bag in the center.<br />
The seine has 1.2-centimeter (cm) mesh in the wings and 0.6-cm mesh in the bag. It was utilized to<br />
sample shoreline waters between the bottom and surface at depths of 0 to 1 m. The seine was<br />
positioned parallel to shore between 8 and 31 m from the water’s edge, depending on bottom contours.<br />
The seine was held in place for 3 minutes and then walked slowly to shore.<br />
Small beach seine in the West MTB.<br />
The small beach seine is a 7.3-m x 1.2 m-net with 0.3-cm mesh, with no<br />
bag. It was utilized to sample waters between 0-1 m in depth on the<br />
shorelines of the MTBs. The seine was positioned perpendicular to the<br />
shore, walked parallel to the shore for a measured distance, then pivoted<br />
in and walked to shore. The length of the each haul was determined by<br />
the space and water available at the time of the sampling and recorded<br />
on the field datasheet.<br />
By the October <strong>2008</strong> sampling period, the muting of the tide by the accreted flood shoal in the inlet<br />
had reduced the tidal drainage in the FTB to an extent that the regular shore-based large beach seine<br />
stations were deeper than suitable at some station replicates. At Station 1, replicate 2 had to be moved<br />
slightly to the west to an area that provided enough exposed beach to pull the net up onto. At Station<br />
2, replicate 1 had to be moved slightly to the west along the shoreline and replicate 3 moved around the<br />
corner to the north to accessed exposed beach as well. Station 2, replicate 1 was therefore not pulled<br />
through eelgrass beds during October <strong>2008</strong>, while in all other quarters the eelgrass bed was sampled.<br />
In <strong>2008</strong>, the MTB fish sampling program was not fully implemented because the basins were not fully<br />
open to the FTB through the tide gates at the water control structure (WCS). The west MTB was<br />
opened to FTB tidal influence in March <strong>2008</strong>, therefore some sampling was done there in April <strong>2008</strong> at<br />
two locations near the tide gate. By July, some tidal water had spilled over from the west to the central<br />
MTB (as designed), so some sampling was done in that basin as well at two locations, though<br />
conditions were non-tidal. Additionally, the WCS was briefly opened to the FTB for several hours five<br />
days prior to the sampling, which likely allowed in some fish. In October, the west MTB was still the<br />
only basin open to tidal influence, however three replicate hauls were collected in both the west and<br />
central basins.<br />
Merkel & Associates, Inc. 38