Definition
Spatially and geographically defined, marine or coastal areas in which specific management measures are applied to sustain important species [fisheries resources] during critical stages of their life cycle, for their sustainable use (UNEP, 2005)
Refugia Concept
- NOT be “no take zones”, ·
- Have the objective of sustainable use for the benefit of present and future generations·
- Provide for some areas within refugia to be permanently closed due to their critical importance [essential contribution] to the life cycle of a species or group of species·
- Focus on areas of critical importance in the life cycle of fished species, including spawning, and nursery grounds, or areas of habitat required for the maintenance of bloodstock
- Have different characteristics according to their purposes and the species or species groups for which they are established and within which different management measures will apply·
- Have management plans
Limiting fishing activity may not be enough to achieve sustainable fishery exploitation due to a non-linear relationship between the animal size and egg production. However, catch restriction of animal of particular size and life stages may potentially maintain the population
Pauly (1997)
The larval development stages of P. monodon consist of 6 nauplius, 3 protozoea and 3 mysis before they entered the juvenile and postlarvae stages (Fig. 5). The larval development of P. monodon takes place at the offshore for they are planktonic. At the end of the postlarvae stage, P. monodon move to the nursery ground at the estuaries which include wide brackish water rivers (mostly upstream and middle portion), mangrove swamps and interior portions of enclosed bays where they become mostly benthic. In this area, shrimps are exposed to wide physico-chemical fluctuations (especially temperature and salinity) (Motoh, 1985).
The tiger prawn refugia is located near the river mouth of Kuala Baram in Miri. This location is next to a mangrove forest with a river mouth nearby. As the region is adrift, the offshore area sloops into deeper depths. The refugia site is placed under Baram Delta Basin, that was a tertiary basin, which developed in Late Eocene times after organic uplift and folding of Crestaceous to Eucene eugosylindrical sediments. Soft to firm silty clay, make up the bottom sediment type (Nagarajan et al., 2015). There are numerous oil and gas projects of SHELL and PETRONAS located near the refugia area.
Besides the oil and gas, there are a few coral reef areas near refugia site, namely the Miri-Sibuti Coral Reef National Park and The Siwa Reef. The Miri-Sibuti Coral Reefs National Park is a gazetted National Park with water depth ranging from 7 to 50 m (23 to 164 ft) at the seaward edge, has an average visibility of 10 to 30 metres (33 to 98 ft) and estimated area coverage was 186,930 hectares.
| Position | Latitude | Longitude |
|---|---|---|
| Point A | 4° 35.40’ | 114° 3.84’ |
| Point B | 4° 42.30’ | 114° 3.96’ |
| Point C | 4° 48.00’ | 113° 58.08’ |
| Point D | 4° 34.74’ | 113° 43.32’ |
| Point E | 4° 22.80’ | 114° 0.60’ |
| Point F | 4° 35.40’ | 113° 59.16’ |
Fishers that were involved in the tiger prawn fishery were divided into artisanal and commercial trawlers, mainly focused on usage of drift net, 3-layered drift net, hook and line and bottom trawling. While drift nets, 3-layered drift nets operate in coastal waters below 5 nautical miles, the bottom trawlers operate until 15 nautical miles to fish. In all cases, tiger prawns are considered as incidental catch, not targeted. However, the landing of tiger prawn has shown an undulating curve and is not stable.
In the life cycle of the mud spiny lobster (P. polyphagus), the juvenile lobsters are usually found along the shallow coastal habitat while the adult lobsters are usually found in the deeper sea bed of East Johor waters. Thus, the adult lobsters are often caught by bottom net trawlers while traditional fishermen such as traps and drift nets operators target the juvenile lobsters. Spiny lobsters are nocturnal animals, which spend most of their time hiding in rocky crevices to avoid predators and only come out occasionally to find food, especially during the night.
Every year, young adult spiny lobsters will embark on a migration to deeper sea from their coastal habitat for breeding and spawning purposes (Alias et al., 2000). This breeding and migration season begins in early July and by August the number of gravid females aggregating in the spawning area will be higher than other time. During this critical moment, the spiny lobster population is susceptible to overfishing due to the risk of capture by the fishermen.
The spiny lobster refugia site is located at the open sea area near Pulau Aur, East Johor. The average water depth at the refugia site is about 40 meters. The bottom sediment type consists of mud and sand or the combination of both. The area is a regular fishing ground frequented by bottom trawl fishermen in the area. Nearby the refugia area are numerous islands with various marine habitats such as coral reef, seagrass meadows and mangrove forest.
The coral habitat commonly found at the surrounding islands near the refugia site are the fringing reef type. The coral reef habitat is important for the spiny lobster life cycle as it serves as a temporary habitat for spiny lobsters during their breeding period and before the final migration to deeper water for spawning.
| Position | Latitude | Longitude |
|---|---|---|
| Point 1 | N 1° 55.000’ | E 104° 30.000’ |
| Point 2 | N 2° 20.000’ | E 104° 30.000’ |
| Point 3 | N 1° 55.000’ | E 104° 50.000’ |
| Point 4 | N 2° 20.000’ | E 104° 50.000’ |
The spiny lobster fishery in East Johor mainly focused on three main gears, namely bottom trawl nets, drift nets and lobster traps. While the drift nets and traps are operated by traditional fishermen in the shallow coastal waters less than 5 nautical miles from the shoreline, commercial bottom trawlers which operate at deeper waters (above 5 nautical miles) do catch spiny lobsters as bycatches in their fishing operation. However, the landing trend of spiny lobsters in East Johor has been on the decline (Figure 8). From an annual landing of more than 330 metric ton in year 1988, the current landing has decreased to less than a third in year 2019 (DOFM, 2021).
Annually, the landing of spiny lobsters usually increases toward the latter part of the year during the onset of the northeast monsoon (October to March). Fishing activities during the monsoon season would likely be affected by the constant bad weather but for those who braved the choppy sea would likely catch more spiny lobsters.
