The encrustation of the spider crab Hyastenus hilgendorfi inhabiting the Suez Canal in relation
to its reproductive biology was studied. This species is considered a by-catch in the area of the
Suez Canal. It has a negative impact on fishing gear and causes severe damage. Specimens were
collected from July 2009 to June 2010. Crabs were sexed and the degree of encrustation was
visually assessed. 1054 specimens were collected, of which 569 (54.0%) were males, 363
(34.4%) non-ovigerous and 122 (11.6%) ovigerous females. 23.7% (250) had no encrustation
while 76.3% (804) were covered. 49.5% (398) of encrusted individuals were males; 41.0% (330)
were non-ovigerous females and 9.5% (76) were ovigerous females. The degree of encrustation
varied with carapace width in ovigerous females. Females outnumbered males by 2.9:1 between
December and April. Berried females and those with ripe ovaries existed in all seasons except
winter. A single reproductive period from June to November was apparent followed by a resting
phase between January and March. The size at which 50% of females were mature was 22.4 mm
CW. Fecundity was found to be related to carapace width. It is concluded that this crab may
engage in podding behavior. The successful establishment of this species in the Suez Canal may
be related to its fecundity, short larval life span and effective camouflage against predatory
fishes. Suggestions for the reduction of the impact of the bycatch of this species on the
traditional fishery of the Canal are discussed.