Pleurobranchaea californica inhabits the coastal Californian waters (15C) at a medium-depth of between 40-1000 feet. These predatory slugs are usually found crawling along the subtrate floor. Over the years, we have arranged trawls either off the LA coast or just off Monterey bay throughout the year. Trawling data collected over the last 10 years (for Monterey Bay) indicate that generally Pleurobranchaea reside in deeper waters greater than 90 ft, given that deep trawls provide the best catches. Historically, the best trawls have been between 36deg 46′- 36 deg 50’N and 121 deg 48′ 75” – 121 deg 53′ W.
Seasonally, these animals are more abundant in late summer, and throughout the Fall (August-November); this is also the time period where we start pulling up small, young animals. This data therefore indicates that P. californica eggs hatch mid-summer, mature during the fall to fully mature adults that are ready for reproduction during the winter months: December-March is the period where we only pull in large adults between 70-200 ml in volume that are actively mating.
Trawling data are extremely useful in determining the distribution density of various slug species on the sea floor – in the case ofPleurobranchaea, this may be the only data available – we actually use this information to model searching behavior.