Species Caught by Gear Type

This section lists the seabird species known to have been caught in each gear type. (Gear types are defined here.) Note that these are only known instances of a species being caught in a particular gear. Each gear type may have had bycatch of species not listed here, but it has never been reported. Additional species may also be susceptible to bycatch in each gear type.

Gear types
Pelagic longline Demersal longline Troll and jig  
Set gillnet Drift gillnet Trammel net  
Trawl-midwater & pelagic Trawl-bottom Pair trawls  
Seine Dredge Lift nets Falling gear
Trap Pots/Korean trap Handlines & harpoons Other

To get a complete list of the species in each category, click on the heading.

Seabird Species Caught in Pelagic Longlines
There are 68 species of seabirds recorded caught in pelagic longlines. Except for King Penguin and a few of the shearwaters, none of these species are deep divers. Ten species are not divers and one of these (Great Frigatebird) never even lands on the water. Of the remaining species, 13 are surface divers, very rarely going further than 1 m below the surface. This suggests that the birds are being caught when the pelagic longline is very near the surface, either when being set or being hauled. There are very effective methods to reduce seabird bycatch when a longline is being set or hauled, primarily the use of bird-scaring lines (tori or streamer lines) or weighting systems.
Two-thirds (44 of 68) of species recorded caught on pelagic longlines are tubenoses (Procellariiformes; the albatrosses, petrels, fulmars, shearwaters, and storm petrels). Almost all species of albatrosses (19 or 21 species) have been recorded caught on pelagic longlines. Many of the remaining non-tubenose species (12) are gulls, skuas, or jaegers (Laridae and Stercoraridae in the Charadriiformes). None of these are diving species, but are rather scavengers. This is further evidence that the birds are being caught when trying to take bait when the line is being set or trying to take items on hooks when the line is being hauled. 

Seabird Species Caught in Demersal Longlines
There are 78 species of seabirds recorded caught in demersal longlines. Although a few species are adept divers (notably, the penguins, some shearwaters, and some shags), a great many of these species are not deep divers. Seven are not diving species, and 13 are surface divers, very rarely going further than 1 m below the surface. This suggests that most the birds recorded caught on demersal longlines are not being caught when the longline is set at depth, but rather when the hooks are near the surface, either being deployed or being hauled. There are very effective methods to reduce seabird bycatch when a longline is being set or hauled, primarily the use of bird-scaring lines (tori or streamer lines) or weighting systems.
The majority (42 of 78) of species recorded caught on demersal longlines are tubenoses (Procellariiformes; the albatrosses, petrels, fulmars, shearwaters, and storm petrels). Almost all species of albatrosses (17 or 21 species) have been recorded caught on demersal longlines. Many species (19) of gulls, skuas, and jaegers (Laridae and Stercoraridae in the Charadriiformes) are also caught. Because few of these are diving species but are rather scavengers, it is further evidence that the birds are being caught when trying to take bait when the line is being set or trying to take items on hooks when the line is being hauled. 

Seabird Species Caught with Trolls and Jigs
There are 18 species of seabirds recorded caught in trolls and jigs. All of the species caught on these gear are divers. Half of them are plunge divers, such as gannets or boobies, that will dive on their prey (in this case, mistaking the bait or jig for their prey) directly from the air into the water. Three of the remaining nine species are surface divers. Therefore, 12 of the 18 species are either plunge divers or surface divers, suggesting that the birds are caught when the bait or jig is near the surface of the water. The remaining six species are also divers, but include pursuit divers.

Seabird Species Caught in Set Gillnets
There are 92 species of seabirds recorded caught in set gillnets. All of these except one (Leach's Storm Petrel) are diving species, and most are highly adept divers. In some taxonomic groups, the majority of species in the group have been recorded in set gillnets. Grebes are rarely recorded being caught in any gear except gillnets, including set and drift gillnets. The species recorded in these nets include:

  • 16 of 23 species of sea ducks
  • All species (5) of loons or divers
  • 15 of 24 alcids (murres, murrelets, guillemots, auklets, and puffins)

Seabird Species Caught in Drift Gillnets
There are 88 species of seabirds recorded caught in drift gillnets. Most of these are diving species, although eight are not. This may be because drift gillnets are more often near the surface where even birds that do not dive may become entangled. Nonetheless, in some taxonomic groups, the majority of species in the group have been recorded in drift gillnets. The alcids appear to be particularly susceptible to being caught in these nets. Grebes are rarely recorded being caught in any gear except gillnets, including set and drift gillnets, and three of the seven species of grebes that enter the marine environment are recorded in drift gillnets.

Seabird Species Caught in Trammel Nets
No seabirds have been recorded as having been caught specifically in trammel nets. However, seabirds may have been caught in trammel nets, but the information not recorded or published.

Seabird Species Caught in Midwater and Pelagic Trawls
There are 30 species of seabirds recorded caught in pelagic and midwater trawls. Almost all of these, 28 of the 30 species, are tubenoses (Procellariiformes), and eight of these 28 are albatrosses. Eight of the overall 30 species, including four of the albatrosses, are either non-diving or very shallow-diving species, suggesting that these birds are being caught only when the net is being hauled and close to the surface. Many of the remaining species may also possibly be caught when the net is near the surface. As for the bottom trawls, this suggests that an important way to reduce seabird bycatch in these trawls would require making changes when hauling the net.

Seabird Species Caught in Bottom Trawls
There are 42 species of seabirds recorded caught in bottom trawls. The large majority of these, 29, are tubenoses (Procellariiformes), and 11 of these 29 are albatrosses. However, 12 of the overall 42 species, including eight of the albatross, are either non-diving or very shallow-diving species, suggesting that these birds are being caught only when the net is being hauled and close to the surface. This suggests that an important way to reduce seabird bycatch in these trawls would require making changes when hauling the net.

Seabird Species Caught in Pair Trawls
There are only three species of seabirds recorded caught in the pair trawls. All three are diving species, although the Gray-backed Storm Petrel is only a shallow diver, and the other two species are not known to dive to great depths (mostly less than 40 m). This suggests that these birds are being caught only when the net is near to the surface, as when being hauled.
Although few species have been recorded caught in pair trawls, it is likely that many species caught in single trawls may also be suspceptible to being bycaught in pair trawls. Therefore, it is best to also consider the species recorded caught in the midwater/pelagic trawls and bottom trawls. This suggests that an important way to reduce seabird bycatch in these trawls would require making changes when hauling the net or when the net is otherwise near the surface.

Seabird Species Caught in Seines
There have been 28 species of seabirds reported caught in seines. Almost all are divers, except three gulls and one frigatebird, although most are not deep divers. Of the 28 species, nine (about one-third) are plunge divers.

Seabird Species Caught in Dredges, Lift Nets, Falling Gear, Hand Implements, and Other Gear
There are only five species that have been reported caught in these gear types. No seabirds have been recorded caught in lift nets or by hand implements. All of the species recorded to have been caught are divers, although most are shallow divers.

Seabird Species Caught in Traps, Pots, and Korean Traps
There are 27 species that have been reported caught in traps and pots. Two species are gulls, which are surface divers. Almost all the remaining 25 species are pursuit divers. These strong, capable divers may reach depths of 90 m, and most of the species dive in the range of depths from 5 to 30 or 40 m. It is therefore likely that these birds may have been caught in the trap or pot while it was set in waters shallower than about 50 m.

Seabird Species Caught on Handlines and Harpoons
There are 56 species of seabirds recorded as having been caught on handlines. Of these, the largest group is the gulls and terns, with 21 species, more than one-third of the total. The cormorants, shags, and boobies are represented by 12 more species. Thirteen species are either not diving species or surface divers, that is, species that do not dive beyond about 1 m depth. These include several albatrosses and most of the gulls and terns. In general, the species recorded as being caught on handlines are not the more adept, deep-diving species. This suggests that most of the birds being caught on handlines are being caught when the hook is fairly near the surface. Exceptions to this general rule may be the two alcids (Common Murre and Marbled Murrelet) and the more deep-diving shearwater species.