Testing an Acoustic Method to Detect and Quantify Abundance of Longfin Squid Egg Masses Using Sidescan Sonar

Lead PI: Mark Borrelli, Center for Coastal Studies

Objectives
To develop an acoustic method for the rapid and accurate detection and quantification of squid eggs on the seafloor.

Methodology
We will detect and quantify squid egg masses in a systematic, reproducible manner using a phase-measuring sidescan sonar (PMSS), collecting collocated sidescan imagery and swath bathymetry. Aggregations of spawning squid and their eggs will be located through fishermen’s reports and trawl surveys. Validation of the sonar approach will be conducted by working with a bottom trawler (research or fishing) to map ahead of the trawl\’s path, as the trawler collects eggs in a net fitted with an underwater camera system, and comparing the three sets of observations (sonar, amount of eggs collected and video imagery) to validate the approach.

Rationale
Nantucket Sound is an inshore spawning ground for squid and supports an economically important seasonal squid fishery. For a sustainable and economically viable fishery, resource managers need to quantify the potential contribution of spawning to exploited populations, which is especially vital for short-lived squid species that may require pre- and within-season abundance estimates for truly effective fishery management. Knowledge of the distribution of squid egg masses could inform spatial management of fishing effort to protect spawning aggregations. A sustainable squid fishery includes both commercial and recreational/subsistence fishing, the latter of which has cultural importance to Massachusetts stakeholders from
underrepresented/underserved communities.