Database Parameter Descriptions

The list below provides a description of each parameter used in the SCRFA Fish Aggregation Database.

 

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Aggregation (Fish Spawning): a grouping of a single species of reef fish that has gathered together in greater densities than normal with the specific purpose of reproducing.

Aggregation duration: The length of time (from hours to months) that the spawning aggregation lasts for.

Area of aggregation: An index to provide details of the two-dimensional substrate area over which the aggregation was observed to form at maximum numbers observed.

Catch Per Unit Effort (CPUE) trend: CPUE is a useful way of quantifying the amount of fish caught in relation to the amount of fishing performed; it is a proxy of abundance. Units depend of the type of fishing, e.g. kgs fish per hook per fisher per hour, number fish caught per 50 m length gill net per day. Changes in CPUE over time can be used to infer changes in the numbers of fish in the spawning aggregation providing certain assumptions are met.

Current status: A qualitative assessment of the Contact’s opinion regarding the current status of the aggregation relative to the past. Categories are: Same (i.e. no change); Increasing; Decreasing, Gone. See Status parameter(s).

Direct - the following are critical spawning signs: spawning, hydrated eggs, postovulatory follicles.

Fish numbers: An index to describe the peak (maximum) number of fish observed for a given species in an aggregation at one time.

Habitat: Smaller scale of site details such as rubble, sand channels, seagrass.

Indirect – other signs that suggest the aggregations have formed for the purpose of spawning such as courtship, colour changes observed exclusively in association with reproduction, multiple gravid females.

Management/Protection: This field indicates whether the aggregation is managed or if the aggregating species is protected in any way during the time that the aggregation forms. Examples include a ban on sales during spawning season, Marine Protected Area (no-take), time/area closure, size limits, landing quota, limited entry, none. Enforcement: The level of enforcement for any management measures i.e. Strictly, Moderately, Lightly, None, Don’t know. Monitoring type: The methodology used to monitor the aggregation. Examples include visual transects, visual point surveys, landings, test fishing, interviews, CPUE, etc. Monitored by: The affiliation of the person monitoring the aggregation, e.g. individual, organization, government department.

Moon phase: The lunar phase (new moon, first quarter, full moon, third quarter) during which aggregations were noted.

Reef geomorphology: The larger scale coral reef type such as Promontory, Drop-off, Reef Crest, Reef Channel, Inner/Outer Reef, or a verbal description.

Resident- where individuals travel a short distance, from their typical site of residence, to the aggregation site taking a few hours or less and where spawning may occur many times a year, or

Sign of spawning: It is important to confirm that the aggregation observed has formed for the purpose of spawning (it is not uncommon to observe a non-spawning aggregation e.g. for feeding). Both direct and indirect indications can be used. Direct signs provide unequivocal evidence for spawning; indirect signs are other indications of spawning that need to be accompanied by supportive information.

Status parameter(s): An explanation of the parameters and data used to deduce the current status of the aggregation. Parameters could include data of the following collected over several years: CPUE, numbers of fish, density, extent of aggregation area, average fish size landed. Any changes in fishing practices that could have caused, at least in part, such changes to occur (e.g. changes in gear type used, introduction of fishery management, etc.) are also included.

Tidal movement: Whether the tide was high, low, incoming or outgoing.

Time of spawning: The time of day at which actual spawning (i.e. egg/sperm release) was observed in the field. Examples include Sunset, Sunrise, Noon, or military time.

Traditional knowledge details: Information on spawning aggregations that have been exploited for many generations.

Transient- where individuals migrate long distances over days or weeks to the aggregation site during a very specific portion of one or two months of the year.

Type of spawning: The type of spawning observed, either pair spawning (male and female pair), or group-spawning (a group of fish rise together in the water column, often comprising a single female and many males).

Type of aggregation: An aggregation refers to a group of fish of the same species gathered together, as indicated by fish densities or numbers being significantly higher than those found during the non-reproductive period.

Visibility: The maximum horizontal underwater visibility when dive surveys were undertaken.

Year discovered: The year the spawning aggregation was first discovered.

Year first exploited: The year the aggregation was first fished.