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Fishery Bulletin 89(3). 1991 



.CA LCASIEU PARI SH 

 CAMERON PARISH 

 GRAND LAKE 



Figure 1 



Locations of stations in southwest Louisiana. Estuarine sta- 

 tions are labeled E and coastal stations are labeled M and D. 

 Station M18 was located on the 10 m isobath and station E5 

 was located at the coastline in Calcasieu Pass. Freshwater 

 was diverted from the intracoastal waterway at station El 

 and pumped to West Hackberry for solution-mining of a salt 

 dome for a Strategic Petroleum Reserve storage site. A 

 pipeline then transported the supersaturated brine to a dif- 

 fuser at station M10A for discharge. 



depths sampled were nearsurface (1-2 m depth) and 

 nearbottom (~5-9m depth). At the shallow station, 

 M21 (5 m depth), and the deep station, M22 (14 m), the 

 nearsurface tows were as described above but the near- 

 bottom tows were modified to reflect local water depth. 

 The bongo frame was rigged with 505 ^m and 333 ^m 

 mesh nets, and both sides had flow meters mounted 

 off-center inside the mouth to estimate the amount of 

 water filtered for each sample. Most sampling was con- 

 ducted during daytime because of contractual re- 

 quirements. One station (Ml 8) was resampled at night 

 on the same day as regular monthly sampling for 9 

 months (June 1981, April-November 1982), to allow 



diel comparisons to be made; station DW was also 

 resampled at night for the final two months. Before 

 sampling at each station, temperature, conductivity, 

 dissolved oxygen, and pH were measured in situ with 

 a Hydrolab 6000 probe at one-meter intervals from 

 ■bottom to surface. 



During the same time period, the nearby Calcasieu 

 Estuary was sampled at 5-6 stations (labelled E1-E5 

 on Fig. 1) monthly for 21 months, February 1981- 

 October 1982. This estuary is very shallow (average 

 high-tide depth <2m), except in dredged channels, and 

 sampling methods were constrained by the shallow sta- 

 tions (Stubblefield and Vecchione 1985). Triplicate one- 

 minute samples were collected with two samplers 

 described and figured by Stubblefield et al. (1984). The 

 primary gear used at all stations was a half-meter ring 

 net with 153^m mesh mounted in a frame designed to 

 eliminate avoidance due to bridle or boat wake. At 

 three stations (E2, E3, and E4), an epibenthic pullsled 

 rigged with 153^m mesh netting was also used for 12 

 months, May 1981-April 1982, to examine vertical 

 distribution in this very shallow water column. Flow 

 meters were used with both samplers to estimate the 

 amount of water filtered for each sample. At each sta- 

 tion, physical parameters were measured similarly to 

 the coastal stations. Sampling was timed to coincide 

 with daytime high tide. 



All samples were sorted for cephalopods. These were 

 identified and individually measured (dorsal mantle 

 length, DML). Standardized abundance in each sample 

 was calculated as the number of L. brevis collected 

 per 100m 3 of water filtered. The 12 samples collected 

 at each coastal station filtered a total of about 150- 

 250 m 3 of seawater. 



The questions that I wanted to address with these 

 data can be grouped into two categories: (1) Descrip- 

 tion of large-scale patterns such as seasonal occurrence 

 and overall distribution of the paralarvae with regard 

 to temperature and salinity, and (2) statistical inference 

 of small-scale patterns of abundance within waters in 

 which the species occurs. Therefore, the data were 

 treated differently depending on the category to be 

 addressed. 



In the first category, the description of paralarval 

 distribution with respect to physical data (e.g., Fig. 3, 

 the temperature-salinity diagram showing occurrence 

 of L. brevis) is based on physical data at the sampled 

 depths of all stations, including negative stations 

 (where no paralarvae were taken), to contrast condi- 

 tions under which they were collected from those where 

 they were not, for all months in which L. brevis was 

 collected at any station. Because the presence of 

 paralarvae is limited in time to a brief period after 

 seasonal hatching, including physical data for months 

 in which they are not hatching would provide no infor- 



