to other countries, mostly Eastern countries. In the same way, other echinoderms
are also captured for aquarium trade (Micael et al. 2009). Mexico is considered
one of the main exporters together with Indonesia, Singapore, Fiji, Sri Lanka,
Philippines and Vanuatu. For instance, the populations of the Atlantic sea star
Oreaster reticulatus, used as souvenir, have declined in the Mexican Caribbean
(Lunn et al. 2008). Also in the Gulf of California there are other sea stars
(P. unifascialis, P. pyramidatus and Pentaceraster cumingi) that are currently
extracted for ornamentation purposes. However, artisanal fishing has no regulations and the limited information available comes from the results of a survey of
the Mexican echinoderm trade. Currently, an estimated 62 stakeholders in Mexico
collect an average of 12,000 sea stars annually for the souvenir industry.
Some studies have focused on the effect of chemicals related to metamorphosis of
commercially important sea urchins. Carpizo-Ituarte et al. (2002) tested the response
of three species of sea urchin (L. pictus, S. purpuratus, and S. fransicanus) to excess
K
+ in sea water as artificial inducers of metamorphosis. The results showed that K
+
was an effective metamorphic inducer in all three species. The response depended on
concentration and length of exposure. Castellanos-Kotkoff et al. (2004) showed the
effect of thyroxine on metamorphosis and the presence of the nuclear receptor
COUP-TF in the larvae of three species of sea urchins (L. pictus, S. purpuratus,
and S. fransicanus) from the Mexican Pacific.
Salas-Garza et al. (2005) summarize some of the basic studies and main
achievements in the larval development of the red sea urchin S. franciscanus in
Baja California. Spawning of red sea urchins was routinely induced with KCl; eggs
were fertilized using a 100,000 sperm ml
-1 solution. KCl proved the most consistent metamorphic inducer, regularly yielding metamorphosis percentages higher
than 90 %. Metamorphosis was considered complete when the functional jaw that
juveniles use for first benthic feeding appeared (as soon as 20 days after induction).
With this method several thousands of red sea urchin juveniles were produced.
Amador-Cano et al. (2006) used artificial inducers to study signal-transduction
pathways involved in metamorphosis of S. purpuratus postlarvae. Participation of
protein kinase C (PKC), G-protein-coupled receptors (GPCRs), and calcium were
investigated during its metamorphosis, showing that the GPCRs may be shared
between the artificial (KCl) and natural (biofilm) inducers.
2.4.1 The Fishery of Sea Urchins in the Baja California
Peninsula, Mexico
The Baja California fishery is based on two species, the red urchin S. franciscanus
and the purple urchin S. purpuratus. Both species are found in the Pacific coast of
North America, including the Baja California peninsula (Ebert and Southon 2003).
The former is one of the largest species in the world, growing to about 200 mm test
diameter, weighing more than 1 kg and can live for more than 100 years. The
purple sea urchin is small, growing to about 70 mm test diameter.
2 The Echinoderms of Mexico
41
are also captured for aquarium trade (Micael et al. 2009). Mexico is considered
one of the main exporters together with Indonesia, Singapore, Fiji, Sri Lanka,
Philippines and Vanuatu. For instance, the populations of the Atlantic sea star
Oreaster reticulatus, used as souvenir, have declined in the Mexican Caribbean
(Lunn et al. 2008). Also in the Gulf of California there are other sea stars
(P. unifascialis, P. pyramidatus and Pentaceraster cumingi) that are currently
extracted for ornamentation purposes. However, artisanal fishing has no regulations and the limited information available comes from the results of a survey of
the Mexican echinoderm trade. Currently, an estimated 62 stakeholders in Mexico
collect an average of 12,000 sea stars annually for the souvenir industry.
Some studies have focused on the effect of chemicals related to metamorphosis of
commercially important sea urchins. Carpizo-Ituarte et al. (2002) tested the response
of three species of sea urchin (L. pictus, S. purpuratus, and S. fransicanus) to excess
K
+ in sea water as artificial inducers of metamorphosis. The results showed that K
+
was an effective metamorphic inducer in all three species. The response depended on
concentration and length of exposure. Castellanos-Kotkoff et al. (2004) showed the
effect of thyroxine on metamorphosis and the presence of the nuclear receptor
COUP-TF in the larvae of three species of sea urchins (L. pictus, S. purpuratus,
and S. fransicanus) from the Mexican Pacific.
Salas-Garza et al. (2005) summarize some of the basic studies and main
achievements in the larval development of the red sea urchin S. franciscanus in
Baja California. Spawning of red sea urchins was routinely induced with KCl; eggs
were fertilized using a 100,000 sperm ml
-1 solution. KCl proved the most consistent metamorphic inducer, regularly yielding metamorphosis percentages higher
than 90 %. Metamorphosis was considered complete when the functional jaw that
juveniles use for first benthic feeding appeared (as soon as 20 days after induction).
With this method several thousands of red sea urchin juveniles were produced.
Amador-Cano et al. (2006) used artificial inducers to study signal-transduction
pathways involved in metamorphosis of S. purpuratus postlarvae. Participation of
protein kinase C (PKC), G-protein-coupled receptors (GPCRs), and calcium were
investigated during its metamorphosis, showing that the GPCRs may be shared
between the artificial (KCl) and natural (biofilm) inducers.
2.4.1 The Fishery of Sea Urchins in the Baja California
Peninsula, Mexico
The Baja California fishery is based on two species, the red urchin S. franciscanus
and the purple urchin S. purpuratus. Both species are found in the Pacific coast of
North America, including the Baja California peninsula (Ebert and Southon 2003).
The former is one of the largest species in the world, growing to about 200 mm test
diameter, weighing more than 1 kg and can live for more than 100 years. The
purple sea urchin is small, growing to about 70 mm test diameter.
2 The Echinoderms of Mexico
41