A population of humpback shrimp inhabiting Drury Inlet, British Columbia, was surveyed in November 2001 and March 2002 with trawl and trap fishing gear. Trawl catches were more representative of the shrimp population than trap catches in terms of age-structure and sex-stage proportions. Shrimp, as much as 81.4 tons, lived on a variety of benthic habitats, including deeper trawlable muddy and shallower untrawlable rocky areas. The shrimp population was comprised mainly of small age 1 shrimp (58% to 66%); the proportion that would be targeted by commercial fishers (i.e., larger older shrimp) was small (3% to 8%). Individual shrimp in the Drury Inlet population were generally smaller than shrimp reported from other areas of the BC coast. Females had not released their eggs in mid November and most (75%) were egg-bearing in mid March. Many more shrimp were in the transitional stage in March (24.9%) compared with November (0.4%). Shrimp numbers declined in trap catches at depths greater than 60 m. In trawlable areas, shrimp were abundant at depths 31 to 40 m and in rocky areas between 21 and 40 m. Egg-bearing females tended to be shallower in March just prior to egg hatch compared with when they were not carrying eggs in November. Males were collected from a broad depth range (11 to 80 m). Shrimp in the transitional stage were collected between 11 and 70 m, with more individuals being collected in shallower areas (11 to 20 m). The natural mortality rate of the population was high (mean M = 2.0). Mean fecundity was 905 ± 377 eggs per individual. We used a curvilinear model to describe the relationship between female size and fecundity. Shrimp with microsporidia infections were found in low prevalence (0.24%) in the sampled population. Humpback shrimp may experience competition for food resources from spiny pink shrimp, prawns, crangons, and eualids. Herring and shiner perch may prey on larval shrimp. Other species that may prey on juvenile and adult shrimp include eelpouts, english sole, sand sole, pricklebacks, giant wrymouths, staghorn sculpins, great sculpins, red rock crabs, and graceful crabs.
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Vol. 24 • No. 1