Hawaii Troll Fishery - MMPA List of Fisheries

U.S. fisheries are classified under the Marine Mammal Protection Act according to the level of interactions that result in incidental mortality or serious injury of marine mammals.

Pacific Islands

Current Classification on the List of Fisheries

Category	III
Estimated Number of Participants	1,124
Target Species	Various species, including tuna, mahimahi, ono, billfishes, etc.
Applicable Take Reduction Plans	None
Observer Coverage	Not observed
Marine Mammal Species/Stocks Killed or Injured	Pantropical spotted dolphin, HI

^ Number of participants estimates are based on state and federal fisheries permit data. The estimated number of participants is expressed in terms of the number of active participants in the fishery, when possible. If this information is not available, the estimated number of vessels or persons licensed for a particular fishery is provided. If no recent information is available on the number of participants, then the number from the most recent LOF is used. NOAA Fisheries acknowledges that, in some cases, these estimations may be inflating actual effort.

*Observer coverage levels include the latest information reported in the most current final Stock Assessment Report (SAR).

¹ Indicates the stock or species is driving the classification of the fishery.

Basis for Current Classification

Several species of marine mammals including bottlenose dolphins, rough-toothed dolphins, and false killer whales have been reported as depredating bait or catch from troll lines, especially if live bait is used (Shallenberger, 1981; Nitta and Henderson, 1993). Depredation behavior may increase the risk of marine mammals becoming hooked or entangled. Stranding records and other information suggest several marine mammal species may be killed or injured in unidentified hook-and-line fisheries (Bradford and Lyman, 2013; Baird et al., 2014), and between 2008 and 2012, three humpback whales (one of which was accompanied by a calf) were documented to be hooked and/or entangled in recreational trolling gear (resulting in non-serious injuries in two whales, and a prorated value of 0.75 serious injury for the third whale and its calf; Bradford and Lyman, 2013). However, at this time, no mortalities or serious injuries to any marine mammal have been attributed to the commercial Hawaii troll fishery.

Some troll fishermen opportunistically fish in close proximity to groups of Pantropical spotted dolphins, and anecdotal information suggests hookings may occur. The fishing technique of trolling in close proximity to groups of Pantropical spotted dolphins, where and when it occurs, presents a heightened risk to the marine mammals. However, this information alone does not provide sufficient evidence with which to conclude that spotted dolphins are being seriously injured or killed on an occasional basis as a result of these practices. An evaluation of this information was described in the 2013 LOF.

Based on an evaluation of information available at this time, there is a remote likelihood of marine mammal mortalities or serious injuries in the commercial troll fishery.

Distribution

Fishing can occur in both state and federal waters year-round, with trips typically lasting less than a day, although larger vessels may make multi-day trips. In 2013, there were 27,494 fishing trips that reported trolling.

Gear Description

Fishing by towing or dragging line(s) with artificial lure(s) or dead or live bait, or green stick and danglers using a sail, surf or motor-powered vessel underway. Can include trolling with bait (dead or alive), trolling with artificial lure, or trolling with green stick.

Generally four to five but occasionally more than six individual lines rigged with artificial lures may be trolled when outrigger poles are used to keep gear from tangling. Lures are generally trolled at 7 – 8.5 knots. When using live bait, trollers move at slower speeds to permit the bait to swim naturally. Pelagic trollers generally fish at an average distance of 5 to 8 miles from shore, with maximum distance of about 30 miles from shore. Trollers fish where water masses converge and where submarine cliffs, seamounts, and other underwater features dramatically change the bathymetry. Trollers often fish drifting logs, other flotsam, underneath bird aggregations, and near FADs.

Management

The fishery is monitored and managed by the Hawaii Department of Land and Natural Resources/Division of Aquatic Resources (DAR), NOAA Fisheries and the Western Pacific Fishery Management Council, as appropriate. In general, fisheries are managed for the species harvested rather than by gear, but in some cases there are specific management measures for particular gear types or methods.

In federal waters, harvest of Western Pacific pelagic management unit species is managed in accordance with the Fishery Ecosystem Plan for Pacific Pelagic Fisheries of the Western Pacific Region and implementing regulations under 50 CFR 665.798 through 665.819.

A commercial marine license issued by DAR is required for all commercial fishing activities. This fishery corresponds to the following fishing method(s) defined by DAR: trolling (trolling with bait, trolling with lures, trolling with green stick).

Historical Information

Original Category (Year added to the LOF)	III (1996)
Original Number of Participants	1,795
Basis for Original Classification	Listed as Category III because the fishery was expected to have a remote likelihood of incidental serious injury or mortality of marine mammals.
Past Names	Split from “HI trolling, rod and reel” in 2015
Species/stocks historically documented as killed or injured (but not currently on the list)	N/A

Timeline of Changes

2024	Estimated number of participants updated from 1,293 to 1,124.
2023	Estimated number of participants updated from 1,380 to 1,293.
2022	Estimated number of participants updated from 2,117 to 1,380.
2016	Estimated number of participants updated from 1,560 to 2,117.
2015	Split the Category III ‘‘HI trolling, rod and reel’’ fishery into two separate Category III fisheries, the ‘‘HI troll’’ and ‘‘HI rod and reel’’ fisheries. Although the gear types used may be similar in some cases, the methods used are different, which may affect the likelihood of encountering or interacting with marine mammals.
2013	Added Pantropical spotted dolphin (HI) based on available fisheries information that indicates they are incidentally injured at low levels. Retained the fishery as Category III fishery because current information does not suggest that total commercial fishery-related mortality and serious injury of the stock exceeds 10% of the PBR of 61 (i.e., 6.1 serious injuries or mortalities per year). NOAA Fisheries bases this conclusion on the following: 1) The lack of mortality/serious injury reports in the Final 2011 SARs and recent bycatch estimates; 2) The reportedly small number of participants in the troll and charter fisheries who opportunistically fish in close proximity to spotted dolphin groups; 3) The limited geographic and temporal scope of dolphin groups that are known to associate with tuna in Hawaiian waters and fished by local trollers; 4) The likelihood that some portion of that trolling effort around dolphins is recreational and would not count toward an estimation of risk that the commercial fisheries pose to the dolphins; 5) The likelihood that not all interactions between dolphins and the troll fisheries are serious injuries, particularly if an animal is snagged in an appendage or in the body by a hook being dragged through the water. A hooking in the body or an appendage, though case specific, is more likely to be a non-serious injury than an ingested hook, according to NOAA Fisheries policy for distinguishing serious from non-serious injury of marine mammals; 6) The lack of any direct evidence of serious injury or mortality of spotted dolphins in the troll and charter vessel fisheries; and 7) The lack of any other identified sources of incidental mortality/serious injury of this stock of spotted dolphins. There have been no observed or estimated mortalities or serious injuries of spotted dolphins in the Hawaii-based longline fisheries within the U.S. EEZ around Hawaii since 2005, though there are an estimated 0.5 serious injuries or mortalities per year in the deep-set longline fishery on the high seas (Carretta et al., 2012b; McCracken, 2011). The fishing technique of trolling in close proximity to groups of Pantropical spotted dolphins, where and when it occurs, presents a heightened risk to the marine mammals. However, this information alone does not provide sufficient evidence with which to conclude that dolphins are being seriously injured or killed on an occasional basis as a result of these practices. Number of participants updated from 2,191 to 1,560.
2012	Proposed to elevate to Category II based on anecdotal reports (from a newspaper article and discussions with marine mammal researchers in the field in HI) of hookings of Pantropical spotted dolphins (HI), NOAA Fisheries and WPFMC reports, the level of effort in the fishery; and proposed to add Pantropical spotted dolphins (HI) to the list of species/stocks killed/injured. Based on the information received from public comments, it was apparent that certain pieces of the new information seem to indicate a Category II classification is not warranted, while other pieces of new information seem to indicate a Category II classification is warranted. The information included: Direct observations and a videotape of troll vessel operations in close proximity to spotted dolphins; information suggesting NOAA Fisheries may have overestimated the distribution and level of commercial fishing effort ‘‘fishing on’’ dolphins; license and trip report data that suggest the frequency at which dolphins are seriously injured may fall below NOAA Fisheries’ projected take estimates; and the author of the newspaper article NOAA Fisheries considered commented that the instance described in the article that he reported on this one instance because he believed it to be a rare event. Therefore, NOAA Fisheries needed additional time to consider and investigate the information provided by the public commenters to better understand the nature and level of interactions. Number of participants updated from 2,210 to 2,191.
2011	Number of participants updated from 1,321 to 2,210.
2006	Number of participants updated from 1,795 to 1,321.

References

Baird, R.W., S.D. Mahaffy, A.M. Gorgone, T. Cullins, D.J. McSweeney, E.M. Oleson, A.L. Bradford, J. Barlow, and A.N. Zerbini. 2014. Evidence of high levels of fisheries interactions for false killer whales around the main Hawaiian Islands: Variations by social groups and correlation with increased mortality levels. PSRG-2014-15. 10 p.

Bradford, A.L. and E. Lyman. 2015. Injury determinations for humpback whales and other cetaceans reported to NOAA Response Networks in the Hawaiian Islands during 2007-2012. NOAA Technical Memorandum NOAA-TM-NMFS-PIFSC-45. 29 p.

Nitta, E.T. and J.R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Marine Fisheries Review 55(2): 83-92.

Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final Report to U.S. Marine Mammal Commission, MMC-77/23. 79 p.

Last updated by Office of Protected Resources on 03/06/2024

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