Figure 1.
Top left-Belize (BZE) and surrounding nations (MEX = Mexico, GUA = Guatemala).
Box contains Glover's Reef Marine Reserve (GRMR). Top right: GRMR showing the location of all receivers (black and white squares). The three primary locations where sharks were tagged are labeled “EL” = Elbow, “MC” = Middle Caye and “SE” = Southern Entrance (see Table 1). Tagging locations for other sharks are denoted by their stars and their tag identification number (see Table 1 for capture and biological information). Bottom: Southern part of the atoll showing more detail of receiver locations.
Figure 2.
Deployment locations for Baited Remote Underwater Video surveys.
(A) Location of the four study sites along the Belizean coast and Mesoamerican barrier reef: Caye Caulker Marine Reserve (CCMR), Turneffe atoll (TU), Southwater Caye (SWC) and Glover's Reef Marine Reserve (GRMR). (B) Still image captured from a BRUV deployment at GRMR with a Caribbean reef shark in frame. (C) Position of BRUV deployments (see symbol legend) at GRMR. (D). Position of BRUV deployments at CCMR.
Figure 3.
The satellite images show the location of the BRUV deployments (see symbol legend, figure 2) made at the two fished sites:
A. Turneffe atoll (TU). B. Southwater Caye (SWC).
Table 1.
Caribbean reef sharks tagged with acoustic transmitters at GRMR.
Figure 4.
Residency index (RI) of Caribbean reef sharks tagged at GRMR with acoustic transmitters.
Individual sharks are denoted by their transmitter code (see Table 1) and are arranged by increasing body size from top to bottom. (*) indicates the shark was fitted with an external transmitter as opposed to having one implanted into its coelom.
Figure 5.
Monthly occurrence of each of the tagged sharks at GRMR.
A square denotes that the individual (transmitter code on y-axis) was detected on at least one day during the given month. The color of the squares indicates the number of days that month that the individual was detected with the scale of white (1–7 days), grey (8–14 days) and black (>14 days). The values are total number of days per month not consecutive days. “T” denotes the tagging time of sharks not tagged in the month of May or June and “*” refers to a break in receiver coverage due to refurbishment or damage.
Figure 6.
Examples of fidelity of Caribbean reef sharks to sites monitored by receivers.
The number of days that all sharks tagged in the specified location were detected anywhere in the array were pooled and then apportioned to receivers. A-Pooled detection days of sharks tagged at Middle Cay (MC); B-Pooled detection days from sharks tagged at Southern Entrance (SE) and C- Pooled detection days of sharks tagged at the Elbow (EL). The height of the bar over each receiver designates the percentage of the pooled days with detections that occurred on that receiver. North is indicated by the arrow. Flat circles show receivers with no detections for any sharks tagged in the specific location.
Figure 7.
The influence of distance of receiver from sharks tagging site on the probability of detection and number of days detected.
(a) Probability of detection from the AIC best model of presence/absence, for a receiver operational for one year, in the ocean reef habitat (b) Lognormal predicted fraction of days observed from the two models combined.
Table 2.
Analysis of deviance for the AIC best model of presence or absence of Caribbean reef sharks by receiver with fixed effects only.
Table 3.
The AIC and BIC values for models with random effects (in bold).
Table 4.
Observed and predicted presence or absence of Caribbean reef sharks based on the AIC best model (days+ldist+habitat+ldist×shark).
Table 5.
Observed and predicted presence or absence of Caribbean reef sharks based on a model including only log-distance and days sampled.
Table 6.
AIC best model of log of days with a detection for the fraction of days each shark was observed at each monitor.
Table 7.
AIC best model of log of days with a detection for models with additional random effects.
Figure 8.
Predicted probability of presence/absence for the AIC best model (solid lines) plus and minus 2 standard errors (dashed lines).
Points are the average values in each month in the data for sharks tagged with V9 (12 month) transmitters and V16 (18 month) transmitters, see symbol legend. The y-axis is the predicted presence or absence of the shark with 0 being absent and 1 being present, the x-axis is the duration since the shark was tagged in months.
Table 8.
The AIC best model for the probability of presence, for the duration since tagged (month) and the battery life of the tag.
Figure 9.
Number of BRUV deployments out of 50 per site in which one (solid portion of bars) or more (open portion of bars) Caribbean reef sharks were recorded at GRMR (reserve), CCAR (reserve), TU (fished) and SWC (fished).
Table 9.
The GLM analysis on the influence of the conservation boundaries (reserve and non-reserve) and location, on reef shark presence or absence derived from BRUV deployments.
Table 10.
The GLM analysis on the influence of the environmental parameters (flow velocity and water temperature) on reef shark presence or absence derived from BRUV deployments within the marine reserve sites.