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Fishery Bulletin 120(2) 
genus apart from other slipper lobsters. They are capa- 
ble of moving long distances by swimming, and their life 
history can be described as nomadic and not directed or 
migratory. Jones (1988) and Courtney et al. (2001) studied 
the mobility of species of Thenus by using tagging. Data 
from recovery of tagged individuals indicate that individ- 
uals of Thenus species can move as far as 24 km in 183 d 
(Courtney et al., 2001). They are more active during late 
evening and early morning, the foraging time of the lob- 
ster (Jones, 2007). 
Most of the species of Thenus mature in 1 year (at about 
45 mm in carapace length for most species) with a fecun- 
dity of up to 67,000 eggs (Jones, 1988; Radhakrishnan 
et al., 2007). Like other tropical species, Thenus species 
breed almost throughout the year, with at least 2 spawning 
peaks, the timing of which might vary in different regions 
(Kagwade and Kabli, 1996; Jones, 2007; Radhakrishnan 
et al., 2007). Flathead lobsters carry eggs in their pleop- 
ods (swimming legs) for about 25 d before releasing phy]l- 
losoma larvae that have a larval life of 30-45 d involving 
4 stages, the last one of which is the nisto stage in which 
larvae molt for settlement. Water currents and eddies 
play a role in the distribution and settlement of Thenus 
larvae because they are mostly retained within the area 
of release as a result of their shorter life in comparison to 
that of palinurid larvae, which are carried long distances 
offshore. 
Flathead lobsters have been caught in the Saudi waters 
of the Arabian Gulf since 1980, yet to date little scientific 
N 
4 
Arabian Gulf 
Saudi Arabia 
100 km 
BHRHEE 
information is available about the biology and population 
dynamics of this species and the fishery that targets it. 
In view of this knowledge gap, this study was carried out 
with the following aims: 1) to determine the spatial distri- 
bution and abundance of flathead lobsters, 2) to examine 
the life history of this species, and 3) to assess the stock 
of flathead lobsters in the waters of Saudi Arabia in the 
Arabian Gulf. 
Material and methods 
Study area 
The Arabian Gulf is a semi-enclosed, shallow sea located 
between the Arabian Peninsula and Iran. It is bounded 
on the south by Oman and the United Arab Emirates, 
on the west by Qatar, Bahrain, and Saudi Arabia, on the 
north by Kuwait and Iraq, and on the east by Iran (Fig. 1). 
It is about 990 km long with a width of 200-370 km and 
an average depth of 36 m. The waters of Saudi Arabia 
in the Arabian Gulf host a great variety of habitats and 
a rich biodiversity, including nursery habitats (Rabaoui 
et al., 2017, 2019; Lin et al., 2021a; Rabaoui et al., 20214), 
coral reefs (Lin et al., 2021b, 2021c), spawning habitats 
(Lin et al., 2021a), and rich pelagic habitats enhanced by 
manmade structures (Rabaoui et al., 2015a) with abun- 
dant mammals (Rabaoui et al., 2021b). 
26°N —— - 
T 0.00 
49°E 51°E indiv/m? (000s) 
T 
49°E 50° 
Figure 1 
A map showing (A) abundance (in thousands of individuals per 100 square meters) and (B) biomass (in grams per 100 square 
meters) of flathead lobsters (Thenus orientalis) sampled in the waters of Saudi Arabia in the Arabian Gulf during trawl surveys 
conducted between 2013 and 2016. Dots indicate stations where surveys were conducted. In the inset, the outlined area in the 
Arabian Gulf indicates the study area. UAE=United Arab Emirates. 
