EXPLORATORY FISHING: Baseline Catch and Bycatch Evaluation
In order to get an idea of what the "redfish catch" composition as well as how much incidental by catch would be experienced using a 4.5" mesh size, structured and monitored exploratory fishing methods were carried out using five commercial fishing vessels every two to three months between May 2011 and January 2012.
The exploratory fishing results indicate that it is possible to harvest redfish using 4.5” diamond mesh without substantial catch of undersized redfish and other commercially important groundfish species. Depth, time‐of‐year, or some other factors appear to have an impact on the catch of undersized redfish though we were not able to isolate these factors.
The size of redfish caught may be further reduced through codend mesh size adjustment or using size‐sorting devices. A size‐sorting grid system may allow smaller redfish to escape at depth which will result in higher survival rates than through codend meshes at the surface. These aspects of research will be carried out in Component 3 and 4 of this project.
- Vessels used their own commercial groundfish trawls, but a relatively small mesh codend (114 mm or 4.5” mesh size, double twine diamond) provided by the project.
- Each vessel fished 4‐5 days: 85 tows (15 to 20 tows per trip (per vessel)).
- Fishing was carried out on traditional redfish grounds throughout the central portion of the Gulf of Maine at depths from 77 fm to 138 fm.
- Two technicians (or NOAA‐approved observers) were on each of the trips to record operational conditions and to sample catch and bycatch.
- The total catch of all species: ~ 234,000 lb
- Redfish comprised 232,380 lb (94.9% of all catch).
- Total kept and landed redfish were 221,957 lbs, or 95.5% of all redfish caught.
- Pollock (Pollachius virens) was the main landed bycatch species (7,307 lb), with 13 other species landed in smaller amounts.
- 14.9% (~4,000 lbs) of total catch (34 species) was discarded.
- Spiny dogfish (Squalus acanthias) accounted for 63.4% of discards.
- Discards of undersized redfish (MLS: 9” or 23 cm) totaled 4.5% of the total redfish catch.
- Total discards of undersized pollock were 2,744.8 lbs.
- Total discards were less than 200 lbs per species for other species.
The exploratory fishing results indicate that it is possible to harvest redfish using 4.5” diamond mesh without substantial catch of undersized redfish and other commercially important groundfish species. Depth, time‐of‐year, or some other factors appear to have an impact on the catch of undersized redfish though we were not able to isolate these factors.
The size of redfish caught may be further reduced through codend mesh size adjustment or using size‐sorting devices. A size‐sorting grid system may allow smaller redfish to escape at depth which will result in higher survival rates than through codend meshes at the surface. These aspects of research will be carried out in Component 3 and 4 of this project.