Juvenile gadoids habitat association and ontogenetic shift observations using stereo-video baited cameras

• Published in: Marine Ecology Progress Series
• Main Authors: Elliott, Sophie A. M., Turrell, William R., Heath, Michael R., Bailey, David M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Environmental Sciences; Mathematics; atlantic cod; Gadus morhua
• Online Access: https://strathprints.strath.ac.uk/59607/; https://strathprints.strath.ac.uk/59607/15/Elliott_etal_MEPS_2017_Juvenile_gadoids_habitat_association_and_ontogenetic_shift.pdf; https://doi.org/10.3354/meps12068

Understanding habitat variables affecting species distribution and survival is essential to their protection. This is especially important in areas where anthropogenic pressures can have a significant direct impact on not only the survival of the species but also damage their habitat. The Firth of Clyde, southwestern Scotland, was an important commercial fishing area for a variety demersal fish species up until 1973. However, stocks have since declined to near-zero despite fisheries measures put in place to aid recovery. Here we report on Stereo Baited Remote Underwater Video (SBRUV) surveys in the Firth of Clyde between June and September in 2013 and 2014 to determine the habitat of juvenile Atlantic cod Gadus morhua, haddock Melanogrammus aeglefinus, and whiting Merlangius merlangus. Habitat predictor variables explored included substratum type, depth, wave fetch, and bentho-demersal species diversity. G. morhua were most abundant in shallow, sheltered areas composed of gravel-pebble containing maerl. Ontogenetic shifts and density dependence were also observed. M. aeglefinus, and M. merlangus predominated over deeper sand and mud. Relative abundances of all three species were positively related to bentho-demersal diversity. This work demonstrates the potential of SBRUV as a non-destructive survey tool under northern-temperate conditions. Our results indicate that spatial conservation measures to benefit demersal fish should be advised by patterns of bentho-demersal diversity as well as physical substratum types.