In 2016 SEASWAP received funding from the Central Bering Sea Fishermen’s Association (www.cbsfa.com) to test a towed hydrophone array as a means to provide fishermen with a real-time method of detecting whale presence on the fishing grounds. For this project we are collaborating with Jonathan Gordon (University of St. Andrews, Scotland) and Thomas Gordon, of the UK, who build these listening systems for industry in the UK.
Beginning in June 2016, Jonathan and Thomas traveled to Sitka from the UK, and brought acoustic hydrophone arrays with them to test on Sitka’s longline fleet. Two trips were taken offshore in which a 200m array of 2 hydrophones was deployed and towed behind the fishing vessel when it reached the black cod grounds. The team was able to detect sperm whales acoustically up to approximately 5 miles from the vessel, and as the vessel continued to move along the shelf edge, a bearing of the whales was acquired. The array coils nicely into a longine tub on deck, can be deployed while the vessel is moving at speeds upwards of 9 knots, and connects to a user-friendly software called Pamguard (www.pamguard.org) that can be used to automatically detected and visualize sperm whale clicks.
Next steps to this project include updating the Pamguard software for specialized use for fishermen in Alaska, and building an additional array to be tested in the fall with SEASWAP. We hope that fishermen could check these arrays out in the future when they depart for fishing trips to deploy and detect if whales are present near the areas they would like to fish. If whales are detected, then can continue moving to an area where they do not hear whales, to minimize effects of depredation on their gear. For more information, please contact us at 907-738-4494, or email firstname.lastname@example.org.
The project involves combined satellite tagging and mobile texting devices for fishermen to have real-time alerts to whale presence during the state-managed black cod fishery in inside waters of Chatham Strait. Participating fishermen will check out In-Reach Satellite mobile texting devices when they go fishing, and text twice daily updates to a shore device of presence and absence of sperm whales in regional “zones” throughout Chatham. In turn, SEASWAP personnel at the shore station will send twice daily messages to In-Reach devices of all fishermen with updates of regional “zones” where whales are reported. All fishermen, vessel names, and exact locations remain classified. Additionally, SEASWAP researchers will attempt to place satellite tags on sperm whales that have been reported in Chatham, and updates of tagged whale positions are available on the Whale Tracker portion of our website here, as well as included in In-Reach texting updates. In this way, longline fishermen in Chatham Strait can hopefully use these tools to avoid fishing near sperm whales and help to reduce the effects of depredation on their catch.
We are now in our second year of the SK grant, and have had success with fishermen avoiding tagged whales, as well as our In-Reach network. Over 30 fishermen have participated in the network, reporting presence and absence of whales, and reports have helped fishermen avoid fishing in areas where whales have been reported. In August and September, SEASWAP will head to Chatham again to tag sperm whales that enter the strait, and assist fishermen with avoiding fishing near whales. For more information, or to check out an In-Reach, please call 907-738-4494 or email email@example.com.
As a continuation of our bycatch reduction projects funded by NOAA, SEASWAP is still looking at ways to use accelerometer chips to detect specific species of fish. In the future the this information could be used to develop a “smart hook” that detects by catch species, and releases them.
The goal of this work was first to build equipment that can attach to longline fishing gear and record video footage of interactions between animals and fishing gear. This equipment includes GoPros, time delay software, deep-water housings, and time-delay powerful external lights. The devices, nicknamed “Tad-Pros” were attached to demersal longline gear in the Gulf of Alaska to attempt to capture footage of sperm whales removing fish from gear; they were also sent to Hawaii with SEASWAP representatives to modify for pelagic longline gear. In Hawaii, footage was captured of false killer whales removing bait from pelagic longlines. You can view this footage on our website here. In the Gulf of Alaska, while no sperm whales were captured on camera, we gathered many highlights of various demersal fish and invertebrates. You can view this footage here[BREP1] and here[BREP2]. In the second BREP project, we looked to explore whether measurements of acoustics and acceleration alone can provide the ability for species identification. We added an accelerometer to the Tad-Pro equipment and deployed on longline gear in the Gulf of Alaska to see how various fish tugging on hooks exhibited different signatures on the accelerometer.
This project evaluated an acoustic decoy technique for reducing sperm and killer whale depredation on longline gear in Alaska. Longline fishing vessels were recorded hauling fishing gear, which is an acoustic cue sperm whales use to locate vessels to engage in depredation. The sounds were loaded onto an acoustic playback device and given to fishermen. They deployed the device some distance from their true fishing gear, on an anchored buoy-line. Acoustic recorders were deployed with the decoy device as well as the fishing set to record whale activity in the area. A radio transmitter allowed fishermen to remotely activate the device at a range of up to 10 miles approximately an hour before they hauled their true fishing haul. Thus whales would be attracted to the decoy, and the fishing vessel would be free to haul their true fishing set in with minimal or no depredation. We analyzed how the distance between the decoy and the true fishing haul affected whale presence at the true fishing haul, the number of whales that arrived at the fishing haul, and the time the haul was whale-free. Statistical significance was achieved with a linear regression (Poisson distribution) with the number of whales arriving at the true fishing haul as the response variable with respect to distance. In essence, the farther the decoy was set from the true fishing haul, the fewer whales showed up at the haul.
SEASWAP Research has focused on key questions:
Through cooperative research with fishermen, government, and scientists the ultimate goal of this study is to provide recommendations for strategies to reduce or eliminate depredation on longline gear by sperm whales.
As a first step towards this goal, information was collected, in collaboration from the fishing fleet, on the timing of interactions seasonally and diurnally, with identification of the sperm whales occurring on the fishing grounds through visual photographic identification and genetic tissue samples.
This research helped define the scope of the problem, understand the ecology of this endangered species, as well as provided baseline information needed for studying depredation mechanisms, cues and, finally, developing solutions to reducing negative interactions.
Sperm whales are often sighted in waters at the continental shelf edge in Alaska, and the fishing port of Sitka is uniquely situated with ready access to these grounds. Sablefish occur on the continental slope and most commercial longliners fish for sablefish in water depths between 250-600 fa (125-300m). The continental shelf off Kruzof, Baranof and Chichagof islands is very narrow; consequently, the sablefish grounds are only 12-20 miles from shore in this area.
The Sitka-based Alaska Longline Fishermen’s Association (ALFA) has taken a proactive conservation approach to try and develop a deterrence system before mortalities occur. Although this research is conducted in the eastern Gulf of Alaska, the results will be communicated wherever interactions occur.
Sperm whales are often sighted in near coastal waters of Alaska, and the fishing port of Sitka is uniquely situated with ready access to interactions. Sablefish occur on the continental slope and most commercial longliners fish for sablefish in water depths between 1200’ and 3,000’. The continental shelf off Kruzof, Baranof and Chichagof islands is very narrow; consequently, the sablefish grounds are only 12-20 miles from shore in this area. Sitka is an ideal location to launch this project as the fishing grounds are easily accessible and much of the fleet (primarily vessels less than 60 feet) is based out of Sitka.
We know that sperm whales are taking sablefish off longline hooks, but how? The questions below are of particular interest, and this study attempted to answer them with the help of acoustics.
An important part of sperm whale research is identifying individuals. That process includes photographing individual whales in the research area, and matching the photos with genetic samples. Individual sperm whales are identified by the unique markings on their backs, sides and undersides of their flukes, and by the shape of the dorsal fins and flukes. These markings are as unique as fingerprints.
The researchers chartered a small, high speed vessel to allow the primary investigator (PI) to take photos and collect genetic samples from sperm whales in the research area. Longline fisherman participating in the study helped the researchers find whales by calling in when they spotted sperm whales on the fishing grounds. Researchers then motored out to the area reported by the fisherman and located the whales using a directional hydrophone. Fishermen also allow SEASWAP researchers to accompany them on their commercial vessels during fishing trips, to collect identification photos of individuals.
Researchers photograph the sperm whales with either a 35mm SLR loaded with high speed black and white film, or a digital camera. Both are equipped with a 300mm telephoto lens. The researchers take field notes on the whales’ behavior, group size, surface activities, dive duration, and level of interaction with gear. Each whale’s information – behavior, photos and skin sample – is entered into a computer database. The best photograph of each individual whale is printed and used in the final sperm whale catalog of individuals. Individual photographs are then compared to all available sperm whale photographs, including catalogs from other areas, to determine if the whales sighted are different or the same whales.
The Gulf of Alaska Sperm Whale ID Catalog has 110 unique individuals at the start of the 2014 field season. A discovery curve shows the rate of new whales being “discovered” or photographed for the first time, is decreasing. This indicates that the SEASWAP team is close to having photographs of most individuals in the Eastern Gulf of Alaska near the study site of Sitka.
Photo caption: GOA-114, photographed by SEASWAP collaborator John Calambokidis on a SEASWAP tagging cruise with Cascadia Research Collective. Copyright SEASWAP 2009.
To further investigate the movements, locations, and destinations of sperm whales associating with longline vessels along the edge of the continental shelf in the GOA, we deployed satellite tags on 10 males in 2007 and 2009. Information on the timing and movement patterns of sperm whales in the GOA may provide a means for fishermen to avoid whales. Over time these longitudinal data will document the most skilled, repeat depredators and give fishermen an option to avoid fishing at known whale hot spots based upon past location data from satellite tags, thus reducing the opportunity for interactions between whales and fishermen in Alaskan waters.
Photo caption: SEASWAP researcher Nellie Warner collects biopsy samples from the NOAA sablefish survey vessel F/V Alaskan Leader, 2006
An important part of sperm whale research is identifying individuals. Comparing genetic profiles is an excellent way to not only identify individuals, but also to understand family relationships between the whales.
Many questions exist regarding sperm whales in the Gulf of Alaska:
The SEASWAP researchers collected skin samples for their genetic tests. Sperm whales commonly slough off skin when they dive. A dip net can scoop skin samples right off the water. But if there is no sloughed skin, researchers can get a small sample (smaller than a pencil eraser) using a biopsy dart shot from a crossbow that grazes the surface of the whale. Some researchers have even used a small piece of stiff scrubby sponge tied onto the end of a pole and scrubbed skin onto the sponge.
The Southwest Fisheries Science Center (SWFSC), which has a library of 750 sperm whale samples from around the world, analyzed the newly collected skin samples.To date, here’s what the SEASWAP team has found:
– 26 samples have been collected in the Gulf of Alaska
– All samples have been genetically identified as male sperm whales
– Samples have come from 13 known individuals, and 13 unknown individuals (no photograph to match individual to catalog number)
Photo Caption: A biopsy dart collects a sample from a sperm whale in the Gulf of Alaska. Copyright SEASWAP, 2004.
In 2003, hydrophone-equipped researchers working on the Southeast Alaska Sperm Whale Avoidance Project (SEASWAP) found that sperm whales are vocally active around fishing boats setting out and hauling in longline fishing gear. The sperm whales make short pulses called ‘clicks’ that seem to allow them to navigate, detect, and forage on individual prey items —in this case, hooked fish. Scientists think certain sounds of longline fishing may actually be attracting the whales. To find out if that’s true, researchers used an acoustical monitoring system to listen in on longline deployments and recoveries.
Long-term acoustic monitoring and tracking has traditionally been expensive, due to the costs of building, deploying, and retrieving an array large enough to detect and track sounds of interest over a few kilometers range. The researchers came up with an elegant solution – use the longline fishing gear itself as the anchor for an acoustical array.
They also used the newest stand-alone, or autonomous acoustic recorders available. The recorder weighs less than half a pound and has the ability to record continuously for up to 17 hours to a 1 GB Flash card. Sperm whale sounds produce a surface-reflected path, or “echo,” from the ocean surface that can be used to locate the animal while using only two acoustic sensors. The array not only detects sounds, but also tracks sperm whales in two or even three dimensions.
A longline vessel out of Sitka was chartered to do the acoustical work. The vessel set out the standard longline fishing gear along the ocean bottom, but when the final anchor was lowered, three recorders spaced 2 meters and 100 meters apart were attached to the anchor rope with electrical tape. They floated at a depth of 200, 198, and 100 m in the water column. The vessel then left the vicinity, leaving the instruments to record any sounds around the set longline gear.
Eight to 20 hours later, the boat returned and retrieved the longline gear and the recorders attached to it. The anchor line without the instruments was hauled in first to permit the vertical array to monitor the acoustic behavior of any whales in the vicinity of the longline as it was retrieved. Finally, the last anchor rope and instruments were recovered. This process was repeated every couple of days over a 3-week period.
The acoustic arrays have shown that the sperm whales appear to be foraging at around 50m when in the vicinity of longlines in the water, whereas they forage at around 250m when no longlines are in the water. It also appears that the sperm whales are attracted to the longline vessels when they were pulling their gear from the water by the noises the engine made while being engaged and disengaged, not by sounds made by the gear or hydraulic winches.
This study is a team effort. In a proactive move, longline fishermen out of Sitka brought the problem to the attention of managers and scientists. Now working on the problem, scientists are including interested longline fishermen in the process of finding answers. One of the ways fishermen are helping is through the SEAWAP Logbooks.
SEASWAP stands for Southeast Alaska Sperm Whale Avoidance Project. The core team includes ten skippers with vessels and crew who have agreed to be the eyes of the scientists while they’re at sea fishing. These fishermen keep a logbook of their sightings and interactions with sperm whales. They count the number of mutilated fish pulled off their lines and note if it looks like sperm whale depredation. The logbook includes pertinent information about their gear and fishing activities, including vessel type, hull type, electronics used and hydraulic system. The fishermen also photograph individual whales and their interactions using weatherproof cameras and film provided by the study. The logbook pages are collected after each fishing trip and summarized into a report by Linda Behnken, director of the Association of Longline Fisherman’s Association and passed on to the researchers.
In addition to the logbooks, participating fisherman are also part of a communications network, radioing the project base station when whales are sighted off Kruzof or Chichagof islands. And when possible, the fishermen collect residual fish parts, if depredation occurs at the surface, and the sloughed skin of sperm whales, if the opportunity arises, using study-issued long handled dip nets.
Team members completed training in photography and data collection, and are compensated for their time and effort.
Collaboration with fishermen gained insight into how many whales were involved, their sex, what fishing behaviors and acoustic cues* may lead to depredation. We found: a median of 90 male sperm whales were present in our study area who actively remove fish from longline gear, if whales are present at the haul there is a high likelihood of depredation, however there is a seasonal effect (reduced early in the season),One-third of all monitored sets (n=124) had whales near the longline gear during the set, soak or haul. Of the hauls with whales, 71% had some evidence of depredation. Depredation was lowest in March and highest during mid summer.
Based on these observations we have derived six low-cost depredation reduction techniques that we propose to quantitatively test over the next two years:
minimize engine cycling while hauling, which seems to attract animals,
deploying anchor lines that have no fishing gear attached (decoys),
acoustic monitoring with a low-cost hydrophone from fishing vessels prior to setting gear,
testing of an existing variant of fishing gear that includes acoustic reflectors and shortened gangions,
changing the time of year the fishermen deploy their gear and
retaining offal onboard until the end of the haulback.
Tentative acoustic observations:
How are whales finding gear?
No distinctive sounds by longline alone or hydraulics
Strongest candidate: way boat is handled
Detection range analysis requires bathymetry (added 2005)
How are whales taking fish?
Visual or acoustic? Very active acoustically
What depth are they taking fish? 50 m vs. 250 m
Are whales targeting dropped fish? Probably
Is avoidance a viable strategy?
Whale detection range at least 10 nm
Using acoustic recorders SEASWAP found sperm whales are alerted to fishing operations by the propeller cavitation sounds made when vessels shift in and out of gear while hauling longlines. This sound travels great distances, and whales can hear this sound from miles away.
SEASWAP captured a whale on video camera at depth fishing off the longline which gave us insights beyond our imaginations as how removal occurs. We suspended a camera on the longline after recovery and kept some of the catch on the line and redeployed the gear. A whale approached the line, grabbed it with its mouth and created tension by moving up the line. This tension created by these actions popped a fish off the line and the whale extracted itself from the line and swam after the unhooked fish. Note that while the whale looks to be spinning on the line, this effect is actually created by the camera spinning.
It is difficult to estimate the loss of fish due to depredation. Estimates of fish loss are generally conservative because it is not possible to attribute an empty hook (because the bait could have been removed or disintegrated or fallen off the hook) to depredation. Additionally it can be difficult to distinguish whether other species, such as sharks, have contributed to the damage or loss of hooked fish. Damage and loss of fish has significant economic and management implications for both fisherman and fishery biologists tasked with assessing fish stocks. In general, depredation by sperm whales seems to be low to moderate, but it is highly variable in extent both among and within fishing areas. The variability became evident the first few years of SEASWAP when fishermen recorded details of fishing effort in logbooks. These data showed catch was higher when whales were present. Sperm whales and fishermen both knew where the good fishing grounds were located. Locations with no whales present were not as productive for fishermen as areas where whales were present even if depredation occurred.
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Straley J, O’Connell V, Behnken L, Mesnick S, Liddle J (2005) Sperm Whale and Longline Fisheries Interactions in the Gulf of Alaska NPRB Project R0309 Final Report
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