The present paper reports the first record of Neoharriotta pinnata and a second record of Satyrichthys adeni from the Gulf of Aden, Republic of Yemen. The record of N. pinnata is a northward extension of its distribution. Satyrichthys adeni was recorded for the second time from the Arabian Sea coast of Republic of Yemen.

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This paper represents the beginning of a reference data base for the long term assessment and control of environmental impacts on the coral reef habitat of the Balhaf Bay, Gulf of Aden, following the development of an industrial complex on the bay. Present results reveal a high surface water temperature in summer with the tendency for relatively low temperature in the winter months. Bottom water temperature undergoes significant seasonal variation, with the annual difference at the two studied stations found to be up to 13.9 • C in the deep station (D), and 11 • C between August and September in the shallow station (F). Winter salinity variation was found not to exceed 0.5 g/l (measurements between 35.7 and 36.2 g/l), though salinity did vary seasonally: increasing at the beginning of the summer monsoon from 35.7 g/l to reach an annual maximum in this region (36.5 g/l) in the first days of July. The general lack of difference in the index of salinity for the studied depths is worth noting. Whatever the reason, such results call for more detailed studies of the habitats under reference.

This study was conducted to confirm the existence, morphological and biological attributes; growth indicators and reproduction of pearl oyster, Pinctada margaritifera in Hadhramout coast. The samples were collected from around coral colony bases from the shore bays of the city of Mukalla, Broom and Bir Ali Islands through the period September 2009-November 2010. 213 specimens were collected from shallow habitat at intertidal zone, subtidal up to more than 15 m in some places. Its morphological characteristics were described. The results show a strong positive correlation (R 2 = 0.9836) between the biometric parameters (ShH and ShL) of P. margaritifera, with an equation of: Shell Length = 0.992 · Shell height 0.995 . The maximum size of the recorded species was180 mm. Growth rates retreated with age from an average of 34.6 mm/2nd year to 3.7 mm/the 7th year. The dominant proportion of ripe mature specimens was recorded in December 2009-March 2010 in females and along two periods in males -January-March and AugustOctober 2010. The data showed that mean gonadic index (GI) transition of males and females followed nearly the same pattern. The results revealed that the occurrence of both adults and juveniles individuals indicates that the Hadhramout coastal environment is suitable for the growth and reproduction of pearl oyster. ª 2014 National Institute of Oceanography and Fisheries. Hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).