Whale shark

Pacific Blue Marlin

Scientific name: Makaira nigricans1994_uw_tag

Blue marlin are the most tropical of all marlins but are distributed throughout the tropical and subtropical regions of the Indian and Pacific Oceans; a single stock is assumed for each ocean. In the Atlantic, blue marlin range from New England to Gulf of Mexico, the Caribbean, and Uruguay; in the Pacific, the are seen from southern California (rarely) to Chile and Hawaii. In common with striped marlin, they are rarely encountered in shallow nearshore waters, preferring blue, oceanic waters.

The blue marlin is the largest of the marlins, common to 11 feet, and known to exceed 2,000 pounds. It is cobalt blue on top shading to silvery white on bottom, although colors can vary by region, leading to the belief that their may in fact be two distinct species - Atlantic Blue Marlin (M. nigricans) and Indo-Pacific Blue Marlin (M. mazara). The upper jaw is elongated in form of a spear, dorsal fin pointed at front end with no spots, and pectoral fin and anal fin are pointed. The lateral line is reticulated (interwoven like a net), making it difficult to see in large specimens. The body of the blue marlin is covered with imbedded scales ending in one or two sharp points.

Migratory behavior of blue marlin was first studied using acoustic telemetry off the Kona coast of Hawaii in 1989, and then with satellite tags in 1994. Both acoustic tracks and satellite tag records indicate that blue marlin prefer the top 30 meters of the water column and remain above the thermocline most of the time (Holland et al., 1990; Block et al. 1992a,b; Block et al. unpublished data). They feed on an assortment of epipelagic organisms including fish (Scombridae, Istiophoridae, Carangidae), squids and decapods (Baker, 1966; Brock, 1984). Blue marlin have extensive geographical ranges, and conventional tagging indicates trans-oceanic movements on a yearly basis are possible.  

Tag and recapture data show that blue marlin travel long distances and routinely make trans-Pacific or trans-Atlantic crossings (Bayley and Prince, 1994, Holts and Prescott, 1998). One recent tag return indicates the first inter-ocean movements (Atlantic to Indian Ocean) for a blue marlin (Prince, unpublished data) that earlier data on genetics suggested occurred (Finnerty and Block, 1992). In the Pacific, blue marlin tagged in Kona, Hawaii have been recaptured in the South China Sea, in the Marquesas, and off the western coast of South America (Holts, pers. comm). Some of these movements have occurred in relatively short time scales.

In August of 1997 a pilot project was undertaken on blue marlin in Pacific waters off the coast of Kona, Hawaii.   In this project the first generation pop-up satellite tags were set for durations of 60-90 days and fish ranged in body size between 130 and 300 lbs.   Three of the tags successfully surfaced and transmitted data, and one fish was caught within a week after release within a mile of the initial tag and release event. Remarkably, one blue marlin traveled from Hawaii to an area west of the Galapagos (a distance of approximately 3000 nm) in 90 days. At the time people doubted a marlin from Hawaii could travel this far. The remaining five tagged blue marlin did not report back for unknown reasons, possibly tag failure due to antenna interaction with the fish or mortality. The tagging data provided a short term view that was consistent with the acoustic tagging data- marlin were primarily fish of the surface 50m but occasionally dove to deeper depths.

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