Research Seeks to Pin Down Where and When Whales Snag on Fishing Gear

by Laurie Schreiber

At their latest meeting, the Atlantic Large Whale Take Reduction Team’s Northeast sub-group continued to work out strategies to minimize the number of deaths and serious injuries caused to large whales by fishing gear.

Members of the team—including representatives of fishery interests, conservation and environmental groups, academic and scientific bodies, state and federal resource managers, and fishery management organizations—met early in December in accordance with a federal law called the Marine Mammal Protection Act. In 1994, amendments to the act required the National Marine Fisheries Service (NMFS) to take steps to protect large whales from human impacts.

The team last met 18 months ago, in April 2009. That same month, lobster fishermen along the Eastern Seaboard were dealing with a new gear requirement that was developed by the team as a strategy to reduce the risk of entanglement to endangered right whales, finback and humpback whales. Fishermen were required to abandon floating groundline and instead use sinking groundline. The requirement was part of the team’s evolving Atlantic Large Whale Take Reduction Plan.

Groundline is rope that connects traps to each other on the ocean floor. “Floating” groundline has some buoyancy that prevents the rope from snagging on rocks. But floating groundline is also a culprit in snagging whales and other animals by their mouths and flukes. “Sinking” groundline stays on the sea bottom.

Many fishermen along Maine’s rocky coast have expressed dissatisfaction with sinking line because of its tendency to snag and chafe on rocks, creating a safety hazard and resulting in lost gear.

Once the groundline rule was in place, the team began a 5-year planning process to better define the risk to whales of vertical endlines and to develop ways to reduce that risk. Endlines lead from the trap on the sea bottom to a buoy on the surface.

Groundline regulation was hastened by an increase in the number of injuries and mortalities to large whales, particularly right whales, which triggered a provision in the Marine Mammal Protection Act to provide additional measures to reduce the risk of entanglement.

With the groundline rule in place to lessen the risk of entanglement, the team developed a lengthier, 5-year timeline to move forward on a rule for endlines.

The timeline is expected to yield a proposed rule by early 2013, with final implementation scheduled for early 2014. Still in the early stages of the timeline, the team is now in the process of gathering data related to vertical line concentration, whale distribution and entanglement locations.

To that end, the data analysis consulting firm Industrial Economics, in Cambridge, Mass., was contracted to produce “co-occurrence” maps. The maps layer together the various factors related to whales and fishing gear—such as whale species, age, behavior and residency time, season, water depth, habitat/ oceanography, density of vertical lines, and gear type and modifications—in order to paint a picture of high-risk areas.

According to the Industrial Economics report, funded by NMFS’ Northeast Regional Office and presented to the team in December, there were a number of factors to be considered in trying to come up with the number of vertical lines in the water. These included the number of vessels in the water and the number of traps used by each vessel, neither of which is accurately reflected in the number of active permits and trap tags that are held by fishermen, the report says. Other factors include variations in the number of traps or strings of traps fished per vessel and per season, and variations in the amount of time that traps are kept in the water. The report said that the greatest concentration of vertical line occurs in state and nearshore waters off Maine, New Hampshire, and Massachusetts, and between July and October.

According to the report, “The probability that an entanglement will occur may depend on the amount of gear deployed in a particular area, whether the gear is actively tended, the behavior in which a whale is engaged when gear is encountered (e.g., whether the whale is feeding), or other factors.

“Similarly, the risk of injury or death in the event of an entanglement may depend on the characteristics of the whale involved (species, size, age, health, etc.), the nature of the gear (e.g., whether the gear incorporates weak links), human intervention (e.g., the feasibility and success of disentanglement efforts), or other variables….The factors that contribute to risk are not fully understood and are difficult to model.”

The report said that, in the absence of direct measures of risk, the model used employs a rough indicator of co-occurrence that was based on the estimated concentration of gear at a particular place and time, and survey data on sightings of large whales in that area at the same time of year.

However, the report also said the model does not measure the probability of an entanglement, nor does it address the risk of injury or death in the event of an entanglement.

Using data from 2008, the maps show that, for any given month along the Maine coast, there could be anywhere from 1,000 to 10,000 vertical lines inshore, with variations by area. From July through November, there is a nearshore area along the midcoast where the number of vertical lines range from 10,000 to 100,000. In general, the inshore waters of Maine, Massachusetts and New Hampshire have the greatest concentration of vertical lines, particularly between July and October.

The report said that there are notable concentrations of higher co-occurrence in the spring and fall, in areas off Cape Cod, and in parts of Massachusetts Bay and the Gulf of Maine. In general, the report said the outer Cape Cod area and the Gulf of Maine show great concentrations of relatively high co-occurrence of large whales and fishing gear.

A NMFS report entitled “Discussion of Vertical Line Management Options,” presented potential scenarios for reducing the number of vertical lines in the water. The scenarios were based on various numbers of traps per trawl—five, 10 or 20; employing one endline rather than two; closing areas or limiting the number of endlines based on the potential presence of right whales; or a combination of measures.

According to the “2008 Large Whale Entanglement and Ship Strike Report” from NMFS’ Protected Resources Division, seven right whales along the Eastern Seaboard showed evidence of entanglement, as well as 18 humpbacks, one finback, two minkes, one sei whale, and two unknown species, for a total of 31 entanglements in 2008.

Preliminary data for 2009 show that there were reports of seven right whales entangled and two had indications of ship strikes in United States and Canadian waters. For humpbacks, the reported numbers were 17 and four; and finbacks three and one. One sei whale and one Bryde’s whale each were reported to suffer a ship strike, and four minke whales were reportedly entangled by fishing gear.

The team also heard reports about potential gear modifications designed either to minimize the number of endlines or lessen their impact on whales.

An evaluation of a device called a “time tension line cutter” was conducted by researchers with the University of New Hampshire’s Center for Ocean Engineering. According to the 2009 report, research was conducted through a pilot study with fishermen and controlled experiments.

According to the report, “The TTLC is a device deployed at the bottom of vertical end lines. It enables the normal loads associated with fishing practices to be applied for a pre-set amount of time then the device severs the end line from the bottom gear. A struggling animal would then be freed and avoiding tissue damage associated with long-term, tightly-wrapped lines, or drowning.” The report concluded that feedback from fishermen indicated that the device was promising and merited further study and improvement.

Other studies were aimed at better understanding large whale and fixed gear interactions. One project, by researchers with the University of New Hampshire Sea Grant program, developed an automated radio frequency identification system using microchip technology embedded in trap lines and a global positioning system, to monitor fixed gear end lines. The goal, said a report by the researchers, would be to offer real-time fixed gear and line identification, haul-back time and location information.

Another method of tracking the location of fixed gear was developed by the Provincetown Center for Coastal Studies and involved the use of coded wire tags, to be woven into rope, as markings on the gear. Both reports said the methods were promising but not yet viable for large-scale deployment.

NMFS provided two reports on further research needs, one from the standpoint of whale research, and the other from standpoint of gear research.

With regard to whale research, priorities included:

• Research on the distribution of large whales throughout their range in U.S. waters, including behavior on the migratory corridor for large whales and breeding grounds for right whales

• Information on the temporal and spatial distribution of large whales, utilizing aerial surveys, vessel surveys, passive acoustics

• Occupancy of large whales in coastal waters of Maine and in the mid-Atlantic, from the coast to EEZ

• Discovery of the principal wintering area for non-calving right whales

• Research on the vertical distributions of both the processes and the prey organisms related to large whale foraging for habitat characterization and predictive modeling

• Development of technical advances/improvements for disentanglement including sedatives and tools

• Research on the development of non-invasive, long-term tracking tags

With regard to gear research, priorities included:

• Research related to reducing risk associated with vertical lines (including lipid soluble rope, thwartable bottom links, the time tension line cutter system, and other technologies)

• Development of a device for gear marking purposes (e.g. bar code, electronic tagging); should handle the rigors of commercial fishing and be easily affixed to the gear

According to a NMFS presentation, a draft management strategy will be submitted to the team at their next meeting in December 2011