Four-dimensional resource partitioning and disturbance at a multi- 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

Cubera snapper Key 1. Nassau 2. Other 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 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