Gear Interactions & Classification

Gear Interactions

Purse seining in the Adriatic Sea, Croatia. Photo by Ulrich Karlowski/Marine Photobank. 

Gear interactions were gleaned from literature searches for each species. For newly split species, we used information from the original species and separated it where possible, usually based on geographic range.

If a species has any sort of known interaction with fishing gear (capture, entanglement, or collision), whether the gear was active or derelict, it receives a Yes for Known  Interactions with Fishing Gear. This information comes from onboard observer records and logbooks (e.g. Robertson & Bell 2002), carcass recovery (autopsy reports, band returns, beached carcasses, museum specimens, or animals collected from fishermen), and interviews. In cases where the primary source has been unavailable, the secondary source is cited and its status as a secondary source is noted.

A marked checkbox in a specific gear category indicates that a species has been documented to have interaction with that gear type, but does not necessarily imply mortality. These individuals may suffer mortality and/or injuries, or may have been released alive; a penguin hooked but released alive demonstrates the species’ susceptibility to the gear. These released alive individuals may or may not have sustained fatal injuries.

In some cases, we have indicated that a species has known interaction with fishing gear, but which specific gear type is not indicated. This is usually because the literature does not provide sufficient description of the gear to place it confidently in one category or another. If an interaction could not be allocated to a particular gear category, the headline Yes is retained for the species, and there may be no further information in the subsidiary gear type category boxes; the Gear Notes box may provide additional information in these cases (e.g. fishing nets). Depending on the presentation of data for a given fishery or recovery, sometimes species (often gulls) or gear types are not possible to disaggregate. In these cases, every effort was made to determine whether the gear could be correctly identified to any of the 18 categories established (see below for descriptions of categories). Sometimes this involved ancillary research on the fishery itself. If it was not possible to discern the depth of an executed trawl or longline set, or to disaggregate interactions by species from a fishery using mixed gear, as much information as possible is provided in Gear Notes.

If a species is considered at risk of capture in a particular gear type by an author, but no known captures are cited, this information is retained in Gear Notes but is not indicated for the gear type (for an example, see Sula sula). If the species’s taxonomic group (usually at the genus level) has been documented interacting with gear within a species’s given range (e.g. Larus spp. in the North Pacific), this is also noted in Gear Notes. In some cases, animals (dead and alive) have been recovered with fishing gear still attached to their bodies. For hooks (usually hand line or longline) we only indicated the relevant category if ingestion is indicated by the literature. For some species, impacts include striking fishing vessels; this is usually caused by disorientation due to night lighting. This information is recorded in Gear Notes and is not considered a gear interaction in and of itself because this is not unique to, and not always caused by, fishing vessels.

Gear types

Lobster trap, Florida, USA.  Photo by Jiangang Luo/Marine Photobank. 

Gear type classifications are based on the FAO International Standard Statistical Classification of Fishing Gear (ISSCFG) Annex M III, 2016 categories but some categories (e.g., the large ISSCFG category 9 called "hooks and lines") have here been further divided to provide greater resolution to fisheries managers with respect to the gear employed and the differential susceptibility of various species. In other cases, where sources rarely or never indicated which gear was used, FAO categories were lumped together. The terms used are discussed below.

Gear types definitions used in this website and the map tool. These in general conform to the draft FAO ISSCFG types, but with some modifications.
Gear Type Draft new ISSCFG category Description
Seines 01-02.9 Seines and surrounding nets, including purse and beach seines
Trawl-bottom 03.11-03.14, 3.19 Includes otter and beam trawls
Trawl-midwater/pelagic 03.21, 03.29-03.9 Includes trawls described as pelagic and those described as "middle depth"
Pair Trawl-bottom 03.15 Bottom pair trawls can be operated in very shallow waters (2-5 meters) or at much greater depth
Pair Trawl-midwater/pelagic 03.22 Carried out in all depths from coastal to offshore areas
Dredges 04 Mechanized and hand dredges
Lift Nets 05 Portable, shore, and stationary lift nets
Falling Gear 06 Cast nets, falling gear, cover pots
Set Gillnets 07.1, 07.4 Anchored nets; mesh may be in midwater or bottom set
Drift Gillnets 07.2 Gillnets that are not anchored to the seafloor, but kept suspended by floats and weights
Trammel Nets 07.5, 07.6 Most commonly used as stationary gear, but may also be used drifting
Traps 07.3, 07.9, 08.1, 08.3-08.9 Includes fyke nets, weirs, encircling gillnets, salmon bag nets
Pots/Korean Traps 08.2 E.g., lobster pots
Handlines and Harpoons 09.1, 09.2, 09.9, 10.1 Includes pole and line used by recreational and sport fishers
Demersal Longline 09.31 Longlines set on or near the seafloor
Pelagic Longline 09.31, 09.32, 9.39 Includes South American techniques for dolphinfish known as "surface longlining"(sensu Bugoni et al. 2009); the Australians and U.S. Gulf of Mexico also refer to these as surface longlines
Troll and Jig 09.4, 09.5  
Other 10 excluding 10.1, 99 Hand implements and other gear