Recruitment of Spiny Lobster, Panulirus argus, off the southwestern PR

 

How is it funded, who administers it?              

 

Why was the survey originally designed?

 

What are/were the intended outcomes/objectives?

 

Describe the temporal and spatial coverage of the survey

Show the geographic coverage (including depth) of the survey (maps are helpful)

 

How often is the survey conducted (annually, biennially, biannually etc)?

 

Is it seasonal?

 

Describe the underlying experimental design

Fixed site or stratified-random (If stratified-random, describe the strata)?

 

Describe the methodology and gear

 

Describe the outputs of the survey

Describe the data outputs & include a discussion of the variance structure of the data

See Below

 

Self-Evaluation of pros and cons of survey

What suite of species does this survey target (what are gaps)?

What are the gear/method biases (catchability, size selectivity)?

 

What are the temporal/spatial limitations?

 

Is this survey expected to continue into the future?

 

It is relatively expensive/inexpensive, logistically difficult/easy?

 

Self-Evaluation of utility of survey for generating information for stock assessment

Spatial/Temporal coverage

 

Data generated: length frequency, spawning stock biomass, mortality etc.

 

Provide any other information that may be relevant to this discussion

 

Provide most relevant documentation (w/PDFs or hyperlinks if possible)

 

Approach 1999

Modified Witham collectors were used. As per Bannerot et a/. (1992), and Butler and Herrnkind (I 992), this collector consisted of a PVC float and substrate, each one holding 6 pages of nylon-webbed unbacked carpet matting (NomadTM, 3M Co. Inc.) 61 x 4.5 x 0.5 cm. The collector was anchored with polypropylene line tied to concrete blocks. A Styrofoam buoy was tied to each corner of the PVC float.

 

Each collector was set in, or adjacent to, Joyuda lagoon, Boquerón Bay, Puerto Real Bay, Punta Ostiones, Playa Buyé, and Cayo Fanduca. The collectors were placed no deeper than 3 meters. A station will consist of one collector and placed approximately 3 km apart from one another. Collectors were sampled at least once every 2 weeks. Collectors were lifted from the water in a mesh bag to catch pueruli that washed out of the filter material. All collectors were thoroughly searched on board the boat and pueruli and juvenile counted. Pueruli were staged as follows: stage I - transparent, stage 2 - semi-pigmented, and stage 3 - pigmented. First stage juveniles will be distinguished from pueruli by their rounded carapace and erect supra orbital spines. This stage was considered as a stage 4 in our samples.

 

For each trip the following data was recorded:

a. Date, time;

b. Latitude and longitude using a GPS (station number);

c. Habitats type under the collector;

d. Weather conditions;

e. Pueruli numbers and stage and/or juvenile numbers and stages;

f. Salinity, turbidity, and temperature at each station.

 

Each station consisted of two Witham collectors (Figure 1). 2003

 

Station 1 – Punta Guanajibo FRL facilities 18º09.615’N 67º11.026’W. Punta Guanajibo is south of the Guanajibo River, being the river south mouth margin. Therefore, fresh water influence to the stations close to this river is high. Water turbidity is high during the raining season. When the prevailing sea current shifts due south water transparency becomes very low. Bottom substrate consists of fine sediment with fairly well developed turtlegrass mats (Thalassia testudinum).

Station 2 – Punta Guanajibo FRL facilities 18º09.312’N 67º11.264’W. This station is located due west of the previous one in direction to shore moving into Bahía (Bay) Bramadero. Distance between these two stations is more or less 200 m.

Station 3 – Bahía Bramadero north 18º08.834’N 67º11.162’W. This station is located near a hard bottom, consisting of rocks near shore more or less located at the center of the bay. The coastline used to be a mangrove-lined, at the present time only a small portion of mangrove remains north of the station site. Water turbidity tends to be less, than the two previous stations, although the distance between them is less than one (1) nm. Bottom substrate consists of highly developed turtlegrass bed and very fine sediment.

Station 4 – Bahía Bramadero south 18º08.411N 67º11.423’W. This station is located near shore about 500 m south of the previous one. Fresh water runoff is higher in this station due to the fact that drainage from inland is located exactly in front of it. Bottom substrate is highly muddy, with sparse turtlegrass mats.

Station 5 – Bahía Bramadero south 18º08.531,N 67º11.003’W. Fresh water runoff is higher in this station due to the fact that drainage from inland is located exactly in front of it. Bottom substrate is highly muddy, with sparse turtlegrass mats.

Station 6 – Escollo Negro 18º08.617’N 67º14.713’W, this is an emerging fringing reef located 4-nm southwest from Punta Guanajibo.

Station 7 – Escollo Negro 18º08.628’N 67º15.020’W, this is an emerging fringing reef located 4-nm southwest from Punta Guanajibo.

Station 8 – Cayo El Ron 18º06.361’N 67º15.791’W. The name of this station comes from an emerging fringing reef located about 4½ nm from shoreline, in front of Punta Ostiones. Bottom substrate consists of fine sediment covered with turtlegrass, and softcoral.

Station 9 - Cayo El Ron 18º06.231’N 67º15.496’W. The name of this station comes from an emerging fringing reef located about 4½ nm from shoreline, in front of Punta Ostiones

Station 10 – Cayo El Ron 18º06.036’N 67º15.564’W. The name of this station comes from an emerging fringing reef located about 4½ nm from shoreline, in front of Punta Ostiones. This station is located west of the two previous ones.

Artificial Habitats

Twenty modified Witham collectors were deployed at ten stations (two collectors/stations).  As per Bannerot et al. (1992), Butler and Herrnkind (1992) and Quinn and Kojis (1997), this collector consisted of a PVC float and substrate, each one holding 6 pages of nylon-webbed unbacked carpet matting (Nomad ä, 3M Co. Inc) 61 x 4.5 x 0.5 cm.  The collector was anchored with polypropylene line tied to concrete blocks.  A Styrofoam buoy was tied to each corner of the PVC float.

Biological growth over the artificial habitats (fouling) was consistent with local flora and fauna. Fouling was permitted to provide a settlement surface similar to surrounding natural environment. Fouling was partially removed when overgrown became too heavy and affect floatation of the artificial habitats.

Each collector was set in, or adjacent to, Bramadero Bay, El Negro Reef, and El Ron Reef.  The collectors were placed no deeper than 3 meters. A station will consist of two collectors placed approximately 50 feet apart from one another. Collectors were sampled at least once every 2 weeks. Collectors were lifted from the water in a mesh bag to catch pueruli that washed out of the filter material. All collectors were thoroughly searched on board the boat and pueruli and juvenile counted.  Pueruli were staged as follows: stage 1 - transparent, stage 2 - semi-pigmented, and stage 3 - pigmented.  First stage juveniles will be distinguished from pueruli by their rounded carapace and erect supra orbital spines. This stage was considered as a stage 4 in our samples.

The study areas were distributed from 18° 09.615’N; 67° 11.026’W to 18° 06.036’ N; 67° 15.564’ W (Fig. 1). Distance from shore varied from approximately 0.5 to 5 nautical miles. The insular platform in this area is from 12-16 km wide; with an average depth of 25 m. Southeast trade winds prevail, resulting in a complex surface water flow dominated by island topography rather than by prevailing wind. In general terms water flow is along the coast from north to south. Emergent coral reefs are more common to the northwest of the study area. They do not comprise more than 10% of the shelf area. The coastline consists of well develop mangrove (Rhizophora mangle) forest at discreet locations, entwine with sandy beaches, and rocky coasts.

 

Methodology 2008

Study 1: Pueruli Settlement

 

1. Seven stations were selected along the west coast platform according to depth and distance from the shoreline (Figure 1.).

 

2. Fifty six modified Witham pueruli collectors (Witham et al, 1968; Pillips et al., 2005) were constructed of rectangular PVC frame with 6 sheets of air conditioning filter materials, each measuring 30 x 30 cm.  Each sheet was folded around the PVC frame making 12 sheets.  A piece of rope was passed inside the PVC frame to keep the frame together in case it broke.  The rope went out through two of the corners of the frame.  The two ends of the rope were nut tightly and a clip loop in the nut (Figure 1.).

Spiny Lobster pueruli collector

Figure 1 – Spiny Lobster pueruli collector

 

3. The collectors were attached with the clip directly to a buoyed line anchored to the bottom.  The line from the collector to the anchored line, used previously, was modified to prevent incidental entanglements of sea turtles.  The anchored line had two buoys, one with the identification number and the other with a DO NOT DISTURB, STUDY ON PROGRESS signed carved on it.

4. Two sets of collectors were deployed at each station, 30 m apart from each other.  Each set consisted of two collectors hooked to an anchored line.  One of the collectors was hook at a depth range between 30-40 feet and the other at a depth range of 60-80 feet, 2m above the sea floor. 

5. Fifty six (56) pueruli collectors were constructed in order to replaced monthly the collectors sampled.  This was done to control overgrowth of other organisms in the structures.  The collectors sampled were taken back to land and placed on the ground to dry with the sun.

6. Collectors were sampled once a month, between the new and the full moon.  For sampling, a diver covered the collector with a fine mesh netting (so the pueruli couldn’t escape), unsnap the collector, and clip it to a line with a buoy, while the replacement collector was placed in position.  Once both collectors were clipped, they were brought to the boat.  The anchored line was clean from organism on each visit.

7. Collectors were search for spiny lobster pueruli.  All pueruli found were counted, classified according to developmental stage (transparent, pigmented and juveniles).  Juveniles were distinguished from pueruli by their rounded carapace and erect supraorbital spines.  The pueruli were kept in a small aquarium and released away from the area of the collectors.

8. Damaged or lost collectors were replaced.

 

Spiny lobster post larvae collector stations 2003

Figure 2. Spiny lobster post larvae collector stations 2003.

 

 

Spiny lobster post larvae collector stations 2003

 

 

 

Table 1 Description of station coordinates, deployment dates and replacements 2008

Station

Id

Latitude

Longitude

Date deployed

A

A1 18°08.113 67°13.704

3-Mar-08

A2 18°08.105 67°13.692

3-Mar-08

A2 18°08.040 67°13.673

5-Aug-08

B

B1 18°05.900 67°14.812

3-Mar-08

B1 18°05.916 67°14.813

29-Apr-08

B2 18°05.915 67°14.791

3-Mar-08

C

C1 18°02.291 67°15.240

3-Mar-08

C2 18°02.231 67°15.260

3-Mar-08

D

D1 18°06.671 67°17.954

3-Mar-08

D1 18°06.728 67°17.968

29-Apr-08

D2 18°06.690 67°17.954

3-Mar-08

D2 18°06.788 67°17.996

29-Apr-08

E

E1 18°07.258 67°18.941

3-Mar-08

E2 18°07.247 67°18.968

3-Mar-08

F

F1 18°05.068 67°18.053

3-Mar-08

F2 18°05.051 67°18.069

3-Mar-08

G

G1 18°02.627 67°18.031

3-Mar-08

G1 18°02.682 67°18.050

19-Aug-08

G2 18°02.661 67°18.033

3-Mar-08

 

 

 

 

Location of stations for the spiny lobster pueruli collector’s study 2008?

Figure 1 Location of stations for the spiny lobster pueruli collector’s study 2008?