Mitigation Resources by Gear

The number of seabirds bycaught in a particular fishery depends on characteristics of the behavior of the seabird species, and therefore how the seabirds will interact with the gear you use. Therefore, once you have identified the key seabird species for bycatch reduction in your fishery area using the map tool, consider the characteristics of those species. Some of the characteristics that may be important are:

  • Diving Depth: If your gear is out of the diving range of seabirds, the likelihood of interactions during deployment is decreased.
  • Nocturnal/Diurnal behavior: If your gear is deployed when seabirds are not actively foraging the likelihood of interactions is decreased.
  • Spatial use of coastal/pelagic areas: If vulnerable species are unlikely to overlap spatially with your gear deployment, the likelihood of interactions is decreased. The birds may visit certain areas only during some times of the year, so avoiding those areas seasonally may reduce bycatch.
  • Gregariousness: As the number of birds attending fishing gear increases, so does the likelihood of interactions.

Once you have identified the key species of seabirds which are most vulnerable and would most benefit from reduction measures in your fishery, the following sections and table will help you determine the most effective bycatch reduction and mitigation methods to use.

Keep in mind that for most bycatch reduction and mitigation methods there may be complex trade-offs. Some mitigation methods may reduce bycatch for one species and increase bycatch for others. This may be the case especially when considering seabird bycatch and non-seabird bycatch (sharks, turtles, cetaceans), because different groups may have very different behavior characteristics towards a particular fishing method.

For All Gear Types

Marine Organism Bycatch Disposal

Seabirds can be attracted to the discard of unwanted fish or invertebrates that are offloaded by fishing vessels. Some techniques to reduce this attraction include waiting until hauling is complete before returning discards to the sea, or discarding bycatch on the side of the ship away from the hauling hatch. 

Offal Management

Seabirds are very often attracted to offal produced when processing seafood while at sea. Offal management techniques include mincing or freezing discards, waiting to offload discards until further sets are not being deployed, and discarding offal on the side of the ship away from the hauling hatch. 

Gull dining on eels caught in net.  Photo by William Folsom/NOAA/MarinePhotobank.  

Colonial Breeding Species

The highly seasonal and highly concentrated nature of colonial-breeding species means that a well-informed seasonal closure could have significant gains in reducing the vulnerability of these species to fishing gear. The World Seabird Colony Register and references specific to each species may be helpful in determining the precise locations of colonies. 

Non-colonial Breeding Species

Seasonal closures of favored foraging grounds during breeding (often associated with undersea features) could benefit breeding birds in particular.  These are still poorly known for many species, but the larger and well-studied albatrosses and penguins generally have more information of this kind in the references specific to each species.   

Time of Day for Setting and hauling Gear

Night-setting may be an effective method for reducing bycatch if the key seabird species forage mainly by day, as most seabirds do. However, approximately one-third of all seabirds will sometimes forage at night. Night-setting is also more effective on nights with low light levels (dark moon or heavy cloud cover).

Night setting has been shown to be effective in some cases in longline fisheries (both pelagic and demersal) and gillnets.

Gear switching

It may be that a different gear type could still achieve good catches of target species and reduce the accessibility of gear to seabirds. For instance, demersal trawls (which apart from seabird bycatch have significant impacts on the seafloor habitat), could be replaced with traps. Such a change was instituted in the California, USA prawn fishery in the early 2000's.  Chuenpagdee et al. (2003) illustrate assessments which could be used to guide such a decision.

  • Chuenpagdee, R., Morgan, L. E., Maxwell, S. M., Norse, E. A., & Pauly, D. (2003). Shifting gears: assessing collateral impacts of fishing methods in US waters. Frontiers in Ecology and the Environment, 1(10), 517-524.

Fleet Communication

Communication amongst vessels can facilitate avoidance of areas experiencing high concentrations of bycatch-susceptible taxa by spatio-temporal pauses in fishing. This technique can provide gains at any level of participation amongst fleet participants, but its effectiveness is increased with increased participation; a good review can be found in O'Keefe et al. (2014).

For Specific Gear Types

The following table can aid you in identifying which bycatch reduction and mitigation methods may be most appropriate for the specific gear type used in your fishery. The table is organized by the gear types as defined here. For each gear type, recommended bycatch reduction methods are given for different categories of seabird behavior (for example, surface feeders vs. deep divers).

Note that we here use the terminology "bird-scaring lines" to refer to the equipment that is sometimes called "tori lines" or "streamer lines" or "bird-scaring lines."

Gear Type Seabird Type Mitigation Method
Seines All seabirds Clean nets before deploying them so birds are not attracted to things already in the net; specific methods not yet tested-see general guidance above.
Trawl-bottom All seabirds Clean nets before deploying them so birds are not attracted to things already in the net. 
All seabirds Net binding and net weighting help the net sink faster and reduce the chances of net entanglement
Larger seabirds Bird-scaring lines or bird bafflers in conjunction with offal management reduce the risk of warp strike and injury.
Trawl-midwater/pelagic All seabirds Clean nets before deploying them so birds are not attracted to things already in the net.
All seabirds Net binding and net weighting help the net sink faster and reduce the chances of net entanglement
Larger seabirds Bird-scaring lines or bird bafflers in conjunction with offal management reduce the risk of warp strike and injury.
Pair Trawl-bottom All seabirds Clean nets before deploying them so birds are not attracted to things already in the net.
All seabirds Net binding and net weighting help the net sink faster and reduce the chances of net entanglement
Larger seabirds Bird-scaring lines or bird bafflers in conjunction with offal management reduce the risk of warp strike and injury.
Pair Trawl-midwater/pelagic All seabirds Clean nets before deploying them so birds are not attracted to things already in the net.
All seabirds Net binding and net weighting help the net sink faster and reduce the chances of net entanglement
Larger seabirds Bird-scaring lines or bird bafflers in conjunction with offal management reduce the risk of warp strike and injury.
Dredges All seabirds Specific methods not yet tested-see general guidance above.
Lift Nets All seabirds Specific methods not yet tested-see general guidance above.
Falling Gear All seabirds Specific methods not yet tested-see general guidance above.
Set Gillnets Surface Feeding Attending nets can reduce seabird interactions.
Shallow Diving Dropped headlines/cork lines may reduce interactions; adding panels of high visibility (either in mesh type or other material) may reduce bycatch. 
Deep Diving Adding panels of high visibility (either in mesh type or other material) may reduce bycatch; reducing net height or profile to the minimum necessary to maintain target catch.  
Drift Gillnets Surface Feeding Reducing net length reduces soak time as well as setting/hauling times;
Shallow Diving Dropped headlines/cork lines may reduce interactions; reducing net length reduces soak time, as well as setting/hauling times; adding panels of high visibility (either in mesh type or other material) may reduce bycatch.
Deep Diving Adding panels of high visibility (either in mesh type or other material) may reduce bycatch. 
Trammel Nets All seabirds Specific methods not yet tested, but approaches similar to those in gillnets are likely to be effective; see also the general guidance provided above.
Traps All seabirds For pound nets, replacing mesh with ropes in the upper
portion of leaders.
Pots/Korean Traps All seabirds Store traps clean and out of reach of seabirds; retrieve all gear deployed to eliminate ghost-fishing. 
Demersal species Escape hatches have not been tested for bird species.
Handlines and Harpoons All seabirds Handlines should not be left unattended. 
Demersal Longline Diving Paired bird-scaring lines are especially effective when used with line-weighting (external or integrated or Chilean system). A secondary method maiy be using an underwater setting chute. Modifications to hauling practices prevent losses as catch returns to the surface.
Surface feeding Line-weighting, offal management, paired bird-scaring lines.  Modifications to hauling practices prevent losses as catch returns to the surface.
Diurnal species Night-setting requires no modification of gear.
Pelagic Longline Diving Paired bird-scaring lines, particularly if used in conjunction with line-weighting; blue-dyed squid bait may also be effective.  Modifications to hauling practices prevent losses as catch returns to the surface.
Surface Feeding Side-setting of lines, in combination with line-weighting and a bird/brickle curtain. Modifications to hauling practices prevent losses as catch returns to the surface.
Diurnal species Night-setting requires no modification of gear.
Troll and Jig All seabirds As for handlines, these should not be unattended; as for pelagic longlines, it is possible that blue-dyed squid bait may be effective in these fisheries.
Other   See general guidance above.

 

Methods Not Yet Demonstrated to Be Highly Effective

Some methods have been suggested and trialed but have not been found to be very effective, or effective only under certain, very specific conditions. These methods usually require further investigation and testing before it can be determined how and when they might be used to reduce bycatch. Unless the methods have been trialed for your specific situation, therefore, the known effective methods given in the table above should be used.

Blue-dyed baits: This is usually recommended only when using squid as bait, because fish baits do not absorb the dye well and therefore do not become dyed blue. Blue-dyed baits may be more effective as a bycatch reduction for sea turtles.

Bait casters: These may be effective when properly used in conjunction with bird-scaring lines. However, they are complex, require training of the users, and there have been concerns about safety of the fishermen using the bait casters. If used, they should only be used as a secondary method in conjunction with bird-scaring lines as the primary method.

Line shooters: Loose lines do not sink as rapidly as lines set the regular way, and therefore may increase seabird bycatch. In addition, there have been concerns about safety of the fishermen using line shooters.