A two-species bioeconomic model is analyzed, but in contrast to most
similar models, there is no biological interaction between the species, only economic.
The interaction takes place in the market where the quantity of either species may affect
the price of the other. The effects of cross-price elasticities on the optimal steady state
and on the optimal paths in the sole-owner case are investigated both analytically
(steady states) and numerically (optimal paths). First, it is shown that if the harvest of
one species has impact on the price of another species, then this has a positive effect on
its steady-state stock. The effect increases with the stock-elasticity in the cost function.
Further, in the case of linear demand functions, the steady state outcome depends solely
on the sum of the cross-price parameters and not their individual values. Secondly, in
the investigation of optimal paths, it is shown that if the harvest of one species has
impact on the price of the other, optimal trajectories reach steady state faster for itself
and slower for the other species. Further, when cross-price elasticities are sufficiently
high, the paths go from being monotonic to feature over- or undershooting.

• Predators in the market: implications of market interaction on optimal resource management