...I (jpsdad) understand harvest mortality is part of the total but was just asking whether harvest of individuals which appear at risk of natural mortality would increase the total. IOWs, if a fish would have died from natural causes anyway perhaps taking the fish by fishing would not increase total mortality (because a fish that would have been lost naturally is harvested instead).
Cody - My understanding and concept of mortality is harvest removals contribute to total mortality.
jpsdad - ““” IOWs, if a fish would have died from natural causes anyway perhaps taking the fish by fishing would not increase total mortality (because a fish that would have been lost naturally is harvested instead).”””
cody- This is IMO confusing or combining harvest and harvest mortality which is why they are or can be considered two types of mortality.
Cody – Harvesting the fish or it dying naturally contributes to total mortality. I think harvesting would not increase the final total mortality but it would contribute to final total mortality. I think this topic is subdividing total mortality into harvest mortality and natural mortality. It is my understanding that fish mortality (harvest & natural) by basic definition is/was established or proposed to primarily measure all basic losses from the community and not established to account for any resultant biomass gains nor predict future gains to the fishery. Mortality, as I understand it,, is just a measure of all numbers lost from the population or from the community as a whole. Mortality is a measure or an estimate of the basic numbers of losses. Repercussions from the losses to my limited knowledge of the literature has not been discussed as common knowledge nor explored with detailed research. If it is well known or researched,, how or where was it explored or proven? I could be easily wrong about this.
“””Also fishing mortality tends to increase growth and condition of survivors and I(jpsdsd) wondered if improved condition could lead to lower mortality of the survivors than might otherwise take place.”””
Cody – Numbers losses depending on type could contribute to later total mortality. Mortality as number losses from a population or from the community does have affects on the remaining fishes probably mostly as beneficial factors and at times maybe some negative factors. I don’t think the actual affects of mortality for increased growth and condition of remaining fish has been tested or has actually been proven based on numbers previously lost. How would it be proven with testing? What would the control group look like compared to the test group? I think this concept at this point is basically theory or as a modeling concept for the resultant benefits of mortality. Someone somewhere has probably already discussed this topic in some form. I think a lot of this is conjecture which is good thinking about this fishery mortality topic.
