A diagnosis now started (12) from geographic designs and shifting out of higher hook speed elements went along to by the Hawaii-mainly based longline fleet implies that the highest abundance portion shift much with the north in the summertime
The bimodal trend out-of cousin month-to-month wealth and exactly how this may connect with spawning and you may reputation regarding dolphinfish appears harder than simply having swordfish otherwise wahoo. Yet not, spawning continues all year round around the islands (14), the problem limit happen late around in next form inside the catch rates, and updates lowest observe during the February.
I advise that new spring height inside catch price and summer decrease in connect and you can status will be about spawning aggregation nearby the Hawaiian islands. Dolphinfish ovaries compiled in the main Hawaiian islands and you can within the highest shallower banking institutions which have low islands or red coral atolls into northwest regarding Northwestern Island destinations all of the come prepared to spawn or had just produced, according to presence out-of hydrated eggs otherwise post-ovulatory follicles. Apparently few ovaries away from dolphinfish collected > 70 mi. (> 130km) of coast created moisturized egg, but the majority of almost every other dolphinfish ovaries was indeed undeveloped or searched becoming reabsorbing this new vitellogenic oocytes prior to that they had hit readiness. (14)
The Sep-Oct limitation spawning reputation coincident having upsurge in coastal hook costs October-November you can expect to originate from a come back to the hawaiian islands of the Hawaiian archipelago changes an excellent nonspawning period offshore. not, the elevated position could also suggest that seafood go back of significantly more energetic waters nearby the southern edge of the subtropical convergence so you’re able to the latest northern. And March-February minimal standing you certainly will reflect opportunity loss throughout cold temperatures spawning.
We postulate two possible migration scenarios which might explain changes in dolphinfish condition. In the first scenario, well conditioned fish enter nearshore (< 50 mi. or < 93 km) waters from the open ocean, and engage in intense reproductive activities, resulting in weight loss. The dolphinfish, now in an emaciated state, return to the open ocean. In the summer, the density of dolphinfish near the main Hawaiian Islands is low, perhaps because they migrate offshore to avoid their main predator, the blue marlin, Makaira nigricans, which increase in numbers in nearshore waters to reproduce (Hopper, 1990). While offshore during the summer, dolphinfish improve their condition during a nonreproductive period. When they return in late September and October, their condition is at their highest level. A similar nearshore-offshore spawning movement for dolphinfish has been suggested by Wheeler and Ommanney (1953), Williams (1953), Kojima (1955), Williams and Newell (1957), and Arocha et al. (1999).
We and thank H
600 mi. (1,a hundred kilometres) on fundamental Destinations on south edge of subtropical convergence front in which productivity is large. There they fatten up and then migrate southward back into the fresh Hawaiian archipelago to reproduce once again nearshore. That it model will be similar to the migration design demonstrated by Oxenford and you can Hunte (1986a). A clearer visualize could possibly get emerge from the longline fleet hook rate research. And February-March standing maxima recommend that profession experts should look having evidence away from an early on peak for the spawning.
I give thanks to the brand new Joined Fishing Department in addition to fishing-boat captains, buyers, and you can employees from the fish market for enabling us to gather research. We are in financial trouble so you’re able to Good. Chun exactly who vigilantly accumulated and precisely filed the content early in the newest day for all of us weeks. Considerably appreciated are the analytical information and you will feedback provided with M. McCracken additionally the crucial comments and examine of plots away from dolphinfish and wahoo CPUE for every step one-knowledge by the step 1-studies a portion of the Hawaii-established fishery provided with D. Kobayashi. Oxenford, K. Bigelow, E. DeMartini, and you may Grams. Dinardo for their useful guidance.
