Here you can change the values of several important parameters for the reproduction.
In brown trout, males and females can spawn several times in a reproduction season: this is accounted for by the first two boxes that let you choose the maximum number of fertilization each sex can reach per year. Typically, a female can spawn from 1 to 4 times (4 times is already very rare). For males, this number can be relatively higher. 10 is a good start, but it could reach 20 (this has been observed in some conditions).
The third box let you decide if reproduction routine will be called more than once per month. Since the Mediterranea module us a monthly time-step, and since reproduction is for the moment spread between November and February, this leads to 4 reproduction events in a year. You can increase this number by setting 2 spawning rounds per month for instance.
The fourth box let you decide what will be the mean operational sex ratio (OSR). This parameter decides how many males will compete for a given female, and therefore will affect male-male competition, as well as female preference expression. It is a parameter of great importance for sexual selection. A mean value of 4 or 5 is what is usually observed in natura. Lower values are possible in some environments (down to 1), as well as higher values (max is 20). In the model, the OSR around a given female will be a random number sampled in a Poisson distribution using the mean OSR as expectancy.
The fifth and sixth boxes let you change female fecundity parameters. The default values originate from ARnaud Caudron & Fédération de Pêche 74 data, as follows:
fecundity = a*(fork length in mm)^b
The “Individualize Juvenile” checkbox let you decide if each fertilized egg will generate a new object in the simulation. Trout produce a large number of eggs, and this may seriously impacts the module performance (for both memory consumption and management, and it will somehow affect the number of operations to perform). If you let this box unchecked, then a “hatch” object will be used, regrouping the data regarding juveniles sharing the same parents on a given spawning occasion. They will be individualized later, and you can choose this deferred instantiation date using the “recruitment age” parameter. This age is given in month. The default value is 9 months. If the user has chosen to include post-zygotic isolation in the simulation, this effect will intervene at 4 months old if the “individualize juvenile” box is checked. If it is unchecked, post zygotic isolation will be deferred to the moment of individuals instantiation.
The “Spawning habitat quality” button will open a window in which you can ponder the efficiency of reproduction by habitat quality at the reach level. It will influence the total number of eggs actually produced by a female.
help_en/mediterranea/gui/medinitreproductionparameters.txt · Last modified: 2014/03/28 09:31 by jlabonne