This database is for a bottom longline (fixed gear) survey executed in the western and central Gulf of Maine targeting complex rocky habitats. The survey is operated from collaborating commercial fishing vessels, and deploys 1 nm sets of traditional 'tub trawl' bottom longline groundfish gear (1000 hooks). Longline gear is deployed at randomly selected stations within selected NEFSC bottom trawl survey (BTS) strata in the western and central Gulf of Maine during the spring and autumn, overlapping temporally with the NEFSC seasonal BTS in that region. Specific ‘hard’ and ‘smooth’ bottom sub-strata were chosen within the BTS strata based on predictive habitat maps that have identified complex habitat at a spatial resolution of @1.3km2 (Manderson et al. 2011). The total number of longline stations are allocated by the overall area of each stratum, as done in the NEFSC BTS, and stations randomly distributed in the ‘hard’ and ‘smooth’ sub-stratum within each stratum. Each set is made for 2 hours, with gear deployed 1 hour prior to the estimated time for slack tide at that location. The ambient current is monitored with an instrument with an accelerometer (also equipped with a compass and thermometer), which is attached to the mainline on each end of the longline (by the last hook). Temperature-depth probes are deployed on the anchor at each end of the longline. Catch weights, fish lengths, and other biological data are collected for all species following standard survey protocols. Biological sampling (for age and reproductive data) is collected for a subset of species and sizes relative to the BTS’s request protocols to fill in data on uncommon species, and less common sizes (i.e. larger individuals) of key groundfish.

The objective of this survey is to provide important information for several species that are not well sampled in BTS or those that are not caught in substantive numbers (targeted) by commercial or recreational fisheries to inform management, Endangered Species Act (ESA) listing decisions, and conservation plan measures. These include cusk, which is a candidate species under the ESA and a data poor stock, as well as Atlantic Wolffish, Atlantic Halibut, and Thorny Skate, which are all NOAA Species of Concern. This survey is designed to increase sampling opportunities for all of these species. Catch and biological data from this survey provides useful supplemental data and indices for other groundfish including white hake, barndoor skate, red hake, spiny dogfish, haddock, Atlantic cod, and smooth skate.