the form of Pk ji = Bj "jk for j = 1, 2 and all i, k. Thus, in the
absence of any a priori assumptions concerning the Bi, i = 1, ..., 5,

parameters across states, non-linear restrictions on the parameters must

be incorporated for correct estimation. If, however, Bi = Pj for all

i, j, this restriction is trivially satisfied and estimation difficul-
ties are greatly reduced.

 The Bi parameters measure the marginal response of total state

catch to small changes in vessel numbers holding fishing power constant.

Given the homogeneity of the fishing process across states and the fact

that the fishing power function serves to "weight" vessels according to

the input characteristics of each state's vessels, the assumption that

i = Bj for all i, j may not be an unreasonable assumption to make. As
stated above, making the assumption Bi = .B for all i, j insures that

the non-linear restrictions on the reduced form parameters are met,

There is also an additional gain realized by assuming that the catch

equations for the GMRFF producing states to take the form


 cit = Ai + Bvit + Xlit + 2 x2it + Uit (52)


Stated in the manner above, the data on vessels, crew sizes and vessel

sizes can be pooled across states. Not only does such pooling generate

considerably more variation in the vectors of regressors, which aids in
parameter estimation, it also creates a sizeable gain in degrees of

freedom. The final specification of the state catch equations given in

euqation (52) illustrates the cross equation restriction corresponding


 6Recall that i.. = i a.. for all i, j. If .. ajk -for all i, k,
 it follows that Bki ji = i "jk for all i, j, k.