Four-dimensional resource partitioning and disturbance at a multi-species reef fish spawning aggregation: Implications for management
Will Heyman Geography Texas A&M University
Association of American Geographers Las Vegas 26 March 2009 Collaborators Björn Kjerfve Shin Kobara
Eloy Cuevas
Phil Lobel Talk Outline
• Reef fish life cycle • Spawning aggregation vulnerability • Multi-species spawning aggregations • 4-D partitioning at Gladden Spit • Site fidelity and disturbance larvae
juveniles eggs
adults spawning aggregation Spawning Aggregations are highly vulnerable to fishing
89o W 88o W 87o W
Mexico
Caribbean 18o N Sea
Belize o Gulf of 17 N Honduras
Belize Barrier Reef Gladden Spit
16o N
Guatemala Honduras 0 30 60 Kilometers Gladden Spit
Multi-species spawning aggregation
Gladden Spit Gladden Spit Reef Crest Reef Shelf Edge Promontory Spawning Site
Spawning Aggregation Site 21 reef fish species partitioned in space and time Spatial partitioning by species
Grouper Dog snapper
Cubera snapper Key 1. Nassau grouper 2. Other groupers 3. Dog snapper 4. Cubera snapper 5. Other species Nassau grouper
Dog snapper
Cubera snapper Cubera snapper
Photo by Douglas Seifert Temporal partitioning
Cubera Snapper at Gladden Spit, Belize
8000
7000
6000
5000
4000
3000
number of fish 2000
1000
0
6-Mar 3-Apr 1-May 8-May 13-Feb 20-Feb 27-Feb 13-Mar 20-Mar 27-Mar 10-Apr 17-Apr 24-Apr 15-May 22-May Date in 2003 = Full Moon Cubera snapper over 6 years: site and temporal fidelity
31.0 10,000 30.0 C) 0 8,000 29.0
6,000 28.0
4,000 27.0 Maximum Number of Fish of Number Maximum 2,000 26.0 Mean Monthly Temperature (
0 25.0 Jun-98 Jun-99 Jun-00 Jun-01 Jun-02 Jun-03 Mar-98 Sep-98 Dec-98 Mar-99 Sep-99 Dec-99 Mar-00 Sep-00 Dec-00 Mar-01 Sep-01 Dec-01 Mar-02 Sep-02 Dec-02 Mar-03 Sep-03 Dec-03 Nassau grouper Grouper temporal partitioning
Nassau grouper at Gladden Spit
300
250
200
150
100 Number of fish
50
0 1-Apr-03 8-Apr-03 4-Mar-03 4-Feb-03 6-May-03 21-Jan-03 28-Jan-03 15-Apr-03 22-Apr-03 29-Apr-03 11-Feb-03 18-Feb-03 25-Feb-03 11-Mar-03 18-Mar-03 25-Mar-03 = Full Moon13-May-03 Date 300 Mycteroperca bonaci 250 Groupers Mycteroperca venenosa 200 Epinephelus striatus
150
100
50 Maximum number of fish 0
10,000 Snappers Lutjanus cyanopterus 8,000 Lutjanus analis
6,000 Lutjanus jocu
4,000
2,000 Maximum number of fish 0
31
30 C) o 29
28
27
Temperature ( 26
25 J F M A M J J A S O N D Month Reef promontories as
Marine Oases
Breeding Feeding
Photo by Douglas Seifert Cubera snapper spawning site 2008 moved in 2008 Original Why? History of Management
• 1920-1980 increasing fishing • 1995 Tourism begins • 2002 Marine Reserve declared – fishing on Cubera stopped – increasing dive tourism • 2007 Cubera aggregation moves What are the impacts of ecotourism on Cubera snapper spawning behavior? Video and audio analysis Divers in aggregations Quantitative analysis of video clips show no impact of divers on behavior Sounds of spawning Cubera snapper Sounds of Boats
May disturb courtship and spawning behavior
Next steps
• Present this talk in community meeting next week • Recommend that diver boats drop divers and do drift dives to reduce sound impacts