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North Carolina Department of Environment Quality

NC Department of Environment and Natural Resources
Marine Fisheries - Dolphin

Marine Fisheries

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DOLPHIN, Coryphaena hippurus

8-point rule

Dolphin

Life History

Dolphin (Coryphaena hippurus), also called mahi-mahi, dorado or common dolphin, are an open water (pelagic) marine species and can be found worldwide in tropical and subtropical waters. They are sight feeders and usually live in the top 50 feet of the water column. They gather around floating debris and flotsam and prefer water temperatures ranging from 70 to 86 degrees Fahrenheit. Adult male and female fish are commonly referred to as ‘bulls’ and ‘cows’ respectively, because of their different shapes and appearance (sexual dimorphic). Mature male dolphin have a high, flat forehead unlike females. The species is short lived (maximum age is 4) and grows rapidly, with some fish reaching lengths of 36 inches by age 1. The state record for dolphin was caught off Cape Hatteras in 1993 and weighed 79 pounds; however, most fish landed in North Carolina weigh between 5 and 25 pounds. Dolphin can become sexually mature by 4 months of age and as small as 14 inches with most fish maturing by 24 inches. They are considered batch spawners, meaning that they will spawn many times throughout the spawning season, maximizing the survival of larval fish. Spawning occurs offshore of North Carolina around floating grass (brown algae known as Sargassum) and debris during the spring and summer months. In tropical areas, dolphin have been known to spawn year-round.

Fisheries

In North Carolina, dolphin are harvested both commercially and recreationally, with recreational harvest far exceeding the commercial landings. Commercially, the species is harvested using longline gear and hook and line trolling gear. Average commercial landings of dolphin over the past 10 years has averaged about 300,000 pounds a year but has varied by almost as much (Figure 1).

Figure 1

Dolphin are routinely targeted by recreational fisherman and are a mainstay for charter boat fleets fishing out of North Carolina. They consistently rank in the top five most landed recreational fish, by weight, and are typically in the number one spot. The primary mode for catching dolphin is to troll artificial and natural baits from vessels around floating debris and weed lines (Sargassum algae bunched along a current edge). Another popular method is to ‘bail’ dolphin which consists of keeping one live fish in the water to attract others to the boat and stir them into a feeding frenzy. The average annual recreational harvest of dolphin in North Carolina waters is about 3 million pounds and has varied by as much as 2 million pounds in the past 10 years.

Figure 2

Management

Dolphin is currently included in the North Carolina Fishery Management Plan for Interjurisdictional Fisheries, which defers to the requirements of the South Atlantic Fishery Management Council Fishery Management Plan for the Dolphin and Wahoo Fishery of the Atlantic. The goal of the plan is to constrain harvest to the current levels in an effort to keep the rate that dolphin are removed from the population unchanged and ensure that no new fisheries develop.

The fishery is currently managed under Amendment 8 and Regulatory Amendment 1 to the original plan. Amendment 8, implemented in 2016, adjusted the allocation of the annual catch limit between the commercial and recreational fisheries by increasing the commercial allocation from 7.54 percent to 10 percent of the total. This adjustment was reflective of allocations established in the original fishery management plan. Regulatory Amendment 1, implemented in 2017, establishes a commercial trip limit of 4,000 pounds for the dolphin commercial sector once 75 percent of the commercial annual catch limit is landed. This regulatory change was pursued after the 2015 commercial landings were met and commercial harvest was closed in late June of that year.

Stock Overview

  • Assessment: No
  • Terminal Year of Last Assessment: NA
    • Overfishing: NA
    • Overfished/Depleted: NA

Currently, no formal stock assessment on dolphin in the U.S. Atlantic has been accepted for management. This is due to a lack of fishery independent data (data collection from sources other than the fishery), uncertainties in the boundaries of the stock, the life cycle of the fish and the lack of jurisdictional cooperation necessary to fully characterize the harvest across the range of the species. An analysis of catch trends indicated that the stock of dolphin in the U.S. Atlantic is in good condition although these results are accompanied with high uncertainty. Time-series data of catch and size of individuals in the fishery indicate no decline of stock abundance or substantial decrease in average size of fish. Dolphin are a fast growing, early maturing fish with high recruitment (number of fish that survive to maturity). These life history characteristics should allow for dolphin to undergo heavy fishing pressure and still maintain the ability to sustain high stock levels.

Research Needs

Research is needed to evaluate the spatial coverage and seasonal abundance of Sargassum, investigate the importance of Sargassum for early life stages of dolphin, improve estimates on growth and reproduction, improve and expand the collection of social and economic data, evaluate the species feeding aspects, develop tagging programs to investigate movement and mortality, evaluate release mortality and effectiveness of minimum size limits.

Links

Management Agencies

North Carolina Division of Marine Fisheries
South Atlantic Fishery Management Council

Fishery Management Plans Amendments, Revisions and Supplements

South Atlantic Fishery Management Council

Stock Assessment Reports

Exploratory Assessment of Dolphin, Coryphaena hippurus, based on U.S. Landings from the Atlantic Ocean and Gulf of Mexico – Appendix B

Contacts

For more information, contact Steve Poland at Steve.Poland@ncdenr.gov
or 252-808-8159
dolphin
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N.C. Division of Marine Fisheries • 3441 Arendell Street • Morehead City, NC 28557 • 252-726-7021 or 800-682-2632

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