Marine Resources Assessment for the Marianas Operating ... - SPREP

AUGUST 2005 FINAL REPORT
♦ Syngnathidae (Pipefishes and Seahorses)
Status—In Micronesia, 37 pipefish and seahorse species are managed in Micronesia as part of
PHCRT by the WPRFMC (2001). Twenty pipefish species and the thorny seahorse (Hippocampus
histrix) occur in the CNMI and Guam (Amesbury and Myers 2001; Myers and Donaldson 2003) and
have EFH designated within the boundaries of the study area (WPRFMC 2001; NMFS 2004c).
Currently, no data are available to determine if pipefishes or seahorses of the PHCRT are
approaching an overfished situation (NMFS 2004a). Some species regularly appear in the aquarium
trade (Paulus 1999). The alligator pipefish (Syngnathoides biaculeatus), banded pipefish
(Doryrhamphus dactyliophorous), and the thorny seahorse have been listed on the IUCN Red List of
threatened species as data deficient in the study area (Vincent 1996a, 1996b; Lourie et al. 2004).
Distribution—Pipefishes and seahorses are circumtropical and temperate in their distribution
occurring in the Atlantic, Indian, and Pacific Oceans in fresh, brackish, and marine waters (Nelson
1994).
Habitat Preferences—Syngnathids are small, inconspicuous bottom dwellers that occur in a wide
variety of shallow habitats from estuaries and shallow sheltered reefs to seaward reef slopes
(WPRFMC 2001). Habitats include seagrasses, floating weeds, algae, corals, mud bottoms, and
sand, rubble, or mixed reef substrate from tidepools to lagoon and seaward reefs (Myers 1999).
Demersal syngnathid populations occur in singly or in pairs at depths ranging from a few centimeters
to more than 400 m, although they are generally limited to water shallower than 50 m (Allen et al.
2003). Juveniles are occasionally found in the open sea in association with floating debris (WPRFMC
2001).
Life History—Spawning by pipefishes and seahorses involves the female depositing her eggs into a
ventral pouch on the male, who carries the egg until hatching at intervals of 3 to 4 days (WPRFMC
2001). Breeding populations occur throughout the salinity range from fresh to hypersaline waters
(Dawson 1985).
4.2.4.3.2 Invertebrate management unit species
♦ Gastropods (Sea Snails and Sea Slugs)
Status—Gastropods consisting of sea snails (prosobranchs, snails of the subclass Prosobranchia)
and sea slugs (opisthobranchs, sea slugs of the subclass Opistobranchia) are managed in Micronesia
as part of the PHCRT by the WPRFMC (2001). Over 1,300 gastropod species (895 prosobranchs and
485 opisthobranchs) occur in CNMI and Guam (Carlson and Hoff 2003; Smith 2003) and have EFH
designated within the boundaries of the study area (WPRFMC 2001; NMFS 2004c). None of Guam’s
prosobranchs are known to be endemic; however, several are endemic to the Marianas. The majority
of the 895 prosobranchs Smith (2003) reported for Guam are marine species. The actual diversity of
marine prosobranchs of Guam and the CNMI is probably much greater than currently known
considering that the majority of prosobranchs less than 3.5 mm in size have yet to be described
(Smith 2003). The topshell gastropod (Trochus niloticus) was introduced after World War II (WWII) in
an effort to establish a commercial fishery (Smith 2003). Currently, it is regulated with size restrictions
and strictly monitored (Hensley and Sherwood 1993). During a cursory survey of Apra Harbor, Paulay
et al. (1997) found 218 gastropod species. The species diversity in Apra Harbor is expected to be
greater (Paulay personal communication).
Distribution—Gastropods are found worldwide in tropical, subtropical, and temperate waters of
marine and freshwater ecosystems (Kay 1995).
Habitat Preferences—Gastropods inhabit all bottom econiches of coral reef ecosystems ranging
from the surfaces of sediments and rocks, dead coral heads, living corals to seaweed thalloms
(Sorokin 1995). The prosobranchs are the most numerous of the gastropods occupying a variety of
reef habitats including soft sediments, rocky and stony littoral/sublittoral areas, reef flat rocks and
4-54