Growth
The mean annual size increase in females was found to be marginally lower at 12 mm CL / year than for males (12.2 mm CL / year) (Mercer, 1973, cited in Hunter, 1999). Other growth rate estimates suggest an increase of 2-14% CL with each moult (Campillo & Amadei, 1978) or as low as 1-2 mm CL / year (Hepper, 1977). Growth increments decrease as individuals approach their maximum size. Growth rates are also likely to vary with temperature, with higher rates apparent in warmer waters (Hunter, 1999).

Size at maturity
In a marine reserve in the Mediterranean, Goñi et al. (2003) found that female Palinurus elephas were able to reproduce at 76-77 mm CL and males were sexually mature at 82.5 mm CL. This size-specific fecundity was considered to be comparable to a lightly fished population off Ireland. In Britain and Ireland, size at maturity is generally larger (see Hunter, 1999). In Cornwall, Hunter et al. (1996) reported the smallest berried female to measure 90 mm CL whereas in Wales, the smallest berried female measured 121 mm CL. The mean size of female, male and berried female Palinurus elephas in Cornwall was reported as 125.6,132.4 and 135mm respectively, and 155.8, 138.7 and 138.6 mm respectively in Wales (Hunter et al., 1996). Mercer (1973, cited in Hunter, 1999) found that 50% female maturity was reached between 82-86 mm CL in Irish Palinurus elephas, the smallest measuring ca 70 mm CL. Female Palinurus elephas are thought to be almost always mature by the time they recruit into the fishery (Hunter et al., 1996).

Migrations
Palinurus elephas is known to undertake migrations to deeper water in the Atlantic (Ansell & Robb, 1977). Females move to deeper waters during egg development and return inshore prior to egg hatching (GoñI et al., 2001). Males are also thought to make onshore-offshore migrations although the timing in relation to female migrations is contentious (GoñI et al., 2001).

Reduced landings, smaller average size and general observations indicate that populations have declined considerably since the 1970's, in south-west Britain at least. Numbers in the Mediterranean have also been reduced (Campillo & Amadei, 1978). Reasons for the decline include possible over-fishing through use of more efficient capture mechanisms such as tangle nets. Environmental conditions may also play an important role (Hiscock, pers. comm., based on observations in Russell, 1973 and Wilson, 1951). Their presence only on coasts bordering the Atlantic suggests a confinement to oceanic waters (Hepper, 1977). Successful recruitment of decapod larvae may be dependent on incursions of more oceanic water (Russell, 1973).

Several observations suggest that the species makes active annual migrations to and from deeper water (e.g. Hunter, 1999). The populations, at least off the west of Ireland, (except perhaps for large males), move offshore into deeper waters late in the year to over-winter with the movement back inshore occurring in spring (Mercer, 1973, cited in Hunter, 1999). Migrations may be triggered by seasonal changes in sea temperature.