Benefits of a replenishment zone revealed through trends in focal species at Glover’s Atoll, Belize

Published source details Tewfik A., Babcock E., Gibson J., Burns P.V. & Strindberg S. (2017) Benefits of a replenishment zone revealed through trends in focal species at Glover’s Atoll, Belize. Marine Ecology Progress Series, 580, 37-56.
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This study is summarised as evidence for the following.

	Action	Category
	Designate a Marine Protected Area with a zonation system of activity restrictions Action Link
	Cease or prohibit all types of fishing in a marine protected area Action Link

Designate a Marine Protected Area with a zonation system of activity restrictions

A site comparison study in 2007–2013 of 11–23 coral reef sites inside Glover’s Reef Marine Reserve, Caribbean Sea, Belize (Tewfik et al. 2017) found that the effects of a protected no-take area on the abundances and sizes of queen conch Lobatus gigas and Caribbean spiny lobster Panulirus argus, compared to the protected general-use zone with only some restrictions, varied with the size of individuals., Inside the marine reserve, 14 to 20 years after its designation, abundance of mature conch (>5 mm lip thickness) increased over time in the no-take sites (from 4/ha in 2007 to 17/ha in 2013), and was greater than in the general-use sites where the change (from 1 to 2/ha) was not significant. Immature conch (<5 mm) abundance increased similarly in no-take (from 4 to 53/ha) and general-use sites (from <1 to 33/ha). The lip thickness of mature conch decreased similarly over time at all sites (from 11 to 9 mm). The shell length of immature conch decreased similarly over time in no-take sites (from 221 to 182 mm) and general-use sites (from 234 to 186 mm). Abundance of legal-size (>76 mm carapace length) and sub-legal (<76 mm) lobsters increased over time in the no-take sites (legal-size: from 6 to 16/ha; sub-legal: from 1 to 3/ha) but did not change in the general-use sites (legal-size: non-significant change from 6 to 5/ha; sub-legal: remained at 6/ha). The size of all lobsters decreased over time in both no-take sites (legal-size: from 120 to 110 mm; sub-legal: from 59 to 52 mm) and general-use sites (legal-size: from 110 to 100 mm; sub-legal: from 59 to 52 mm). Glover’s Reef Atoll was designated as a Marine Reserve in 1993 and included a no-take area (79.6 km²) and a general-use area with fishery restrictions (including: ban on the use of SCUBA to collect any seafood, closed seasons, and size limits for queen conch and spiny lobster). Once a year in April–June 2007–2013, conch and lobsters were surveyed at 1.6 m average depth inside the no-take area (6–18 sites/year) and inside the general-use zone (5 sites/year). At each site (0.04–1.43 ha), snorkelers counted and measured all conch (shell length; lip thickness) and lobster (carapace length).

(Summarised by: Anaëlle Lemasson & Laura Pettit)
Cease or prohibit all types of fishing in a marine protected area

A site comparison study in 2007–2013 of 23 coral reef sites inside a marine reserve in the Caribbean Sea off Belize (Tewfik et al. 2017) found that the effects of prohibiting all fishing for 14–20 years on fish density, biomass and size varied with level in the food chain of five representative fish species/groups, compared to fished reserve zones. Data were presented graphically and as statistical results. Trends over time showed increases in average fish densities (fish/ha), biomasses (g/ha) or sizes (length to tail fork, mm) in the unfished zone compared to the fished zone: for large, and small, plant/algae-eating fish (Scaridae spp.), one invertebrate-eating fish (hogfish Lachnolaimus maximus) and two of three predatory (fish and/or invertebrates) fish (Nassau grouper Epinephelus striatus and black grouper Mycteroperca bonaci). Average density and biomass of the other predatory species (mutton snapper Lutjanus analis) showed no clear trends over time in the unfished zone, but size decreased. Black grouper density decreased, and biomass remained steady in both the unfished and fished zones, and small herbivores decreased in both unfished and fished areas over time. Diffferences between the unfished and fished zones were generally greater for the species at lower levels of the food chain (e.g. plant/algae eaters). Glover’s Reef Atoll was established as a Marine Reserve in 1993 and has several management zones including no-take (80 km², all fishing banned), and general use (270 km², fishing permitted, with regulations – see original paper for details). Fish in five no-take patch reefs and six fished reefs were monitored between 2007–2009, increased in 2010–2013 to include 12 additional fished reefs. Each reef was sampled once a year during April, May, or June. Fish number and estimated size over the entire area of each reef down to 3 m was recorded by snorkellers.

(Summarised by: Natasha Taylor)