Figure 1.
Locations of pelagic longline sets in the Gulf of Mexico.
Each grey square indicates where one or more longline sets were recorded by fishery observers on commercial longline vessels (n = 2662 sets) within the 1×1° area (we are unable to show locations of individual sets due to privacy concerns). Each red circle indicates a single longline set during our laboratory's cruises on longline vessels targeting bluefin tuna for tagging (n = 112 sets).
Figure 2.
Numbers of bluefin and yellowfin tuna per longline set.
Histograms show the number of (A) bluefin and (B) yellowfin tuna caught in each longline set.
Table 1.
Description, mean, standard deviation (SD), and range of environmental parameters used in this study.
Figure 3.
Mean and relative bluefin and yellowfin tuna CPUE.
Circles indicate monthly mean (A) catch per unit effort (CPUE) of bluefin (closed circles) and yellowfin tuna (open circles) in the Gulf of Mexico, and (B) mean ratio of number of bluefin to 100 yellowfin caught. Error bars indicate 1 sd (based on 1000 bootstrap samples).
Figure 4.
Spatial variability of bluefin and yellowfin tuna CPUE.
Catch per unit effort (CPUE) of (A) bluefin and (B) yellowfin tuna are indicated by size of circles. Crosses indicate locations where more than 5000 hooks were set but no fish were caught.
Figure 5.
Bluefin tuna CPUE in relation to sea surface height anomaly and sea surface temperature.
Histograms show mean catch per unit effort (CPUE) of bluefin tuna in the Gulf of Mexico, with respect to (A) sea surface height anomaly, and (B) sea surface temperature of the longline set. Error bars indicate 1 sd (based on 1000 bootstrap samples).
Figure 6.
Annual bluefin and yellowfin tuna CPUE.
Histograms show annual mean catch per unit effort (CPUE) of (A) bluefin and (B) yellowfin tuna in the Gulf of Mexico, from 1993 to 2005. Error bars indicate 1 sd (based on 1000 bootstrap samples).
Table 2.
Parameters and estimated coefficients of final bluefin tuna model.
Table 3.
Parameters and estimated coefficients of final yellowfin tuna model.
Figure 7.
Yellowfin tuna CPUE in relation to wind speed.
Histograms show mean catch per unit effort (CPUE) of yellowfin tuna in the Gulf of Mexico, with respect to wind speed of the longline set. Error bars indicate 1 sd (based on 1000 bootstrap samples).
Figure 8.
Expected probability of catching bluefin tuna.
Colors indicate the expected probability of catching one or more bluefin tuna in the Gulf of Mexico on 15 May (A) 2002 and (B) 2005. Circles indicate actual relative bluefin tuna CPUE for May 2002 and 2005. Crosses indicate locations where at least one longline set was deployed but no fish were caught.
Figure 9.
Expected probability of catching yellowfin tuna.
Colors indicate the expected probability of catching one or more yellowfin tuna in the Gulf of Mexico on 15 May (A) 2002 and (B) 2005. Circles indicate actual relative yellowfin tuna CPUE for May 2002 and 2005. Crosses indicate locations where at least one longline set was deployed but no fish were caught.
Figure 10.
Map of sea surface height anomalies.
Colors indicate sea surface height anomalies on 15 May (A) 2002 and (B) 2005.
Table 4.
Sensitivity analysis of environmental parameters on the probability of catching one or more BFT and YFT.