Parrack. Estimating stock abundance from size data 327 



(3) If neither occurred, the fish survived; go to step 8B. 



9 If fishing occurs just once each period, then 



A If ti<Cti, the fish recruited before the catch. 



(1) Draw u where u~U(0,l). 



(2) If u<l-e-^ti(<=ti-ti), the fish exited unobserved events before date q; STOP. 



(3) If not, the fish survived to the catch date; go to step 9F. 



B If ti = Cti , the fish recruited on the catch date; go to step 9F. 



C If ti>Cti, the fish recruited after the catch. 



(1) Draw u where u~U(0,l). 



(2) If u< l-e'^ti(yti*i-ti), the fish exited due to unobserved events before the next abundance 

 sample (date yt+i); STOP. 



(3) If not, the fish survived fishing and so was ahve on the next sampHng date: t = t+l. 



D Add a fish to the abundance matrix. 



(1) to = yt. 



(2) Si = lower bound of the minimum size-class. 



(3) Compute the size-class from equation (1). 



(4) Nt,32 = Nt,32 + 1. 



(5) Ift = T, STOP. 



E Draw u where u~U(0, 1). If u<Pr[z']t, the fish exited due to unobserved events before the date of 

 catch; STOP. 



F Draw u where u~U(0,l). If u<Pr[C]t, the fish was caught on date Ct. 



(1) t2 = q. 



(2) Sj = lower bound of the minimum size-class. 



(3) Compute the size-class when caught from equation (1). 



(4) Ct,,2 = Ct,s2+1- 



(5) STOP. 



G Draw u where u~U(0,l). 



(1) If u<Pr[z']t, the fish exited due to unobserved events before the next abundance sampling 

 date; STOP. 



(2) If not, the fish survived to the next relative abundance sample date. 



(a) t = t-i-l. 



(b) Go to step 9D. 



Collect samples once each trial: 



10 Draw an extimate of the growth parameters such that 

 p[A,k] = -0.95, 



k ~ NOik. Mk(cv[k]^-t-cv[ek]2)divg, and 

 A '^ NO^A, MA(cv[A]2 + cv[eA]2)±g. 



11 Draw an extimate of catch for all t and s where Ct,s'^N(Ct g, Ct^ cv[C]2). 



12 For each t and s draw qt,s,k~N(qs, (qg cv[q]2) for l<k<r. 



13 Calculate Yt, sand s2[Yt,s]. 



14 Determine the largest sampled size-class. 



