  Long range dependence or long memory is a feature of many processes in the
natural world, which provides important insights on the underlying mechanisms
that generate the observed data. The usual tools available to characterize the
phenomenon are mostly based on second order correlations. However, the long
memory effects may not be evident at the level of second order correlations and
may require a deeper analysis of the nature of the stochastic processes.
  After a short review of the notions and tools used to characterize long range
dependence, we analyse data related to the abundance of exploited fish
populations which provides an example of higher order long range dependence.
