Choosing the right catch metric
[]The metric should come from the fishery
Before designing the questionnaire, the field team should ask local partners and fishers a simple question: “When people talk about a good fishing or harvesting day here, what unit do they use?” The answer will often reveal the best BECCA metric.
If people say “we count the number of fish”, use number of fish. If they say “we sell by basket”, record baskets and convert them. If they say “we remember the biggest one”, include a size metric. If they say “we rarely land the fish, but we know how many shots or hookups we had”, use encounter metrics. If they say “the catch depends on how many traps were soaked overnight”, use catch per trap per soak or catch per trap per day.
The table below provides guidance, but it should not be treated as a fixed template. BECCA should be adapted to local fishing practice.
Table 1. Types of fishery with possible best catch metrics.
| Fishery type | Possible BECCA metric | Effort variable | Practical note |
|---|---|---|---|
| Recreational sight fishing | shots, follows, eats, hookups, landed fish, maximum size | hours fished per angler | Useful where fish are not always landed. Early encounter metrics may reflect availability better than landed catch. |
| Recreational bait or lure fishing | bites, hookups, landed fish, released fish, kept fish, maximum size | hours fished per angler | Separate landed, released, and retained fish where possible. |
| Catch-and-release fisheries | encounters, bites, hookups, landed fish, fish length or weight | hours fished per angler | Do not rely only on harvest because harvest may be zero. |
| Small-scale handline fishery | number of fish, weight, baskets, boxes, bundles | hours fished per fisher or crew; number of hooks | Record hook number if this strongly affects catch. |
| Net fishery | number of fish, weight, baskets, boxes | soak time, net length, mesh size, hours fished | Gear details strongly affect catch. |
| Seine or drag net fishery | weight, number of fish, baskets, boxes | number of hauls, hours, crew size, net size | Catch may be standardised per haul as well as per hour. |
| Trap, pot, or basket fishery | number of individuals, weight, baskets | number of traps, soak time, hours checking traps | CPUE may be catch per trap per day. |
| Fish fence or weir fishery | number of fish, weight, baskets, sacks | days set, tide cycles, fence length, number of fishers | Effort may need a locally defined unit. |
| Gleaning | buckets, bags, bowls, number of individuals, weight | hours gleaned per person | Record whether catch is individual, household, or group catch. |
| Shellfish or invertebrate harvesting | number of individuals, weight, bags, buckets, baskets | hours harvested per person; area harvested if known | Size metrics may be shell length, carapace width, or market grade. |
| Diving fishery | number of individuals, weight, sacks, bags | dive hours, number of divers, number of dives | Separate boat time from underwater search time if possible. |
| Multi-species artisanal fishery | total catch weight, species-specific catch, baskets, boxes, sacks | hours fished, gear, crew size | Record species groups clearly. |
Gleaning and invertebrate harvesting
In gleaning and invertebrate harvesting, catch is often remembered in containers rather than formal weights16,17. A female gleaner may say that her best day was “four buckets of cockles”, “two bags of clams”, or “a basket of crabs”. These are valid BECCA responses if the unit is documented clearly.
A hypothetical BECCA in a coastal invertebrate gleaning community might begin with a short conversation about how people usually describe a good collecting day. If most harvesters talk in buckets, the survey should use buckets first and then ask how large the bucket is, whether it is a household bucket or market bucket, and approximately how many invertebrates or kilograms fit in one full bucket. The interviewer might also ask whether the bucket is filled to the top, whether mud and shell are included, and whether the same bucket is used by most people.
The best current-year question might be:
“Thinking about this year, what was your best day collecting cockles on the flats? How many buckets did you collect, how many hours were you out, and how many people were collecting with you?”
The historical question might be:
“Thinking back across your collecting life, what was the best day you ever had? What year was that, how many buckets did you collect, and how many hours were you collecting?”
In this example, the analysis could produce buckets per person-hour, estimated kilograms per person-hour, or estimated individuals per person-hour. If shell size is important, a size question could ask about the largest shell or the typical size class that people remember from different periods.
Artisanal and small-scale fisheries
In artisanal and small-scale fisheries, catch units may vary by gear, species, community, and market. One community may describe catch by number of fish, another by boxes, another by baskets, and another by sacks or bushels 7. The survey should accept the locally meaningful unit and then document it carefully.
A hypothetical BECCA in a small-scale handline fishery might ask fishers about their best day catching reef fish. A fisher might report that in 1998, their boat caught six baskets in a day using handlines on the outer reef. The interviewer would then ask how many people were on the boat, how many hours they fished, how many hooks were used if known, what size basket was used, and whether six baskets represented the whole boat or the fisher’s individual share. The same respondent would then be asked about their best day in the current year using the same species group and method.
A hypothetical BECCA in a trap fishery would need a different effort measure. If the catch depends mainly on the number of traps and soak time, the core indicator may be catch per trap per day rather than catch per hour.
The question might ask:
“In your best trap fishing day this year, how many crabs did you catch, how many traps were set, and how long had they been soaking?”
A historical version would ask for the same information in the respondent’s best ever year.
A hypothetical BECCA for a fish fence or weir fishery may need to use tide cycles or days set as the effort unit. If a fisher says the best catch came after a spring tide, the interviewer should record the number of tide cycles, the number of people involved, and whether the catch was from one fence, one section of fence, or a shared community structure.
Recreational fisheries
In some recreational fisheries, especially sight-based fisheries, landed catch may be a poor indicator of fish abundance. A fishing day involves several stages: finding fish, having an opportunity to cast, getting a follow, getting an eat, hooking the fish, landing the fish, and then releasing or keeping it 18. Each stage can fail for reasons unrelated to abundance. Weather, visibility, fisher skill, line breakage, handling, or fish behaviour may determine whether a fish is landed 14.
For this reason, BECCA can use earlier-stage interaction metrics. In South Florida, respondents were asked separately about their best day in terms of shots, and size3. The survey made clear that the best day for shots and the largest fish could all fall in different years. This matters because each metric captures a different part of the fishing process. Shots represent fish opportunities to cast, which occurs before landing and can therefore be less affected by fight duration, gear failure, or handling than landed catch alone.
For recreational fisheries, the field team should work with fishers to identify the interaction metrics that are widely understood. A tarpon fisher may speak naturally about eats and hookups. A bonefish fisher may speak about sightings, shots, or follows. A lure fisher may speak about bites and landed fish. The words should come from the fishery.