Diet, resource partitioning and gear vulnerability of Hawaiian jacks captured in fishing tournaments
Abstract
Stomach content, capture method and capture location data were collected for 401 carangids captured during three annual 1-day fishing tournaments held at a coastal bay in Hawaii. Blue jack ( Caranx melampygus), white jack ( Caranx ignobilis) and island jack ( Carangoides orthogrammus) were the most common species, accounting for 83.5, 8.5 and 5.2% of tournament catches, respectively. Geographical area fished consisted of a sheltered bay and the adjacent seaward coastal reef beyond. Area of capture and fishing method influenced species and size of fish captured. Small (<350 mm fork length) C. melampygus and C. ignobilis predominated in catches within the sheltered embayment indicating this may serve as a nursery area for these species. Conversely most C. orthogrammus and all large (>500 mm) C. melampygus were captured outside Kaneohe Bay. Trolling (towing a surface lure) accounted for 80% of C. melampygus, 76% of C. orthogrammus and 55% of C. ignobilis captured. Differential vulnerability to trolling may be related to interspecific differences in diet; captured C. melampygus had fed primarily on fish whereas C. orthogrammus had consumed both fish and benthic crustaceans, and C. ignobilis had eaten mainly benthic crustaceans. Differences in diet may indicate resource partitioning between these sympatric and closely related species. For C. melampygus there was a consistent relationship between prey size and predator size. When conducted under scientific scrutiny, fishing tournaments can provide synoptic data on diet and gear vulnerability that would otherwise be very difficult to obtain.
- Publication:
-
Fisheries Research
- Pub Date:
- January 2001
- DOI:
- 10.1016/S0165-7836(00)00285-X
- Bibcode:
- 2001FishR..53..105M
- Keywords:
-
- Carangidae;
- Diet;
- Fishing tournament;
- Capture vulnerability