userguide: Weightjones uses maxcons, not consumption

[lentinj]

@bthe Any thoughts on this? the C in the WeightJones documentation seems flat out wrong to me.

Instead of C, we actually use Fphi[i] * MaxCon[i]:

gadget2/src/growthcalc.cc

Line 340 in 508b993

Wgrowth[i] = Fphi[i] * MaxCon[i] * tempC / (pow(numGrow[i].W, wgrowthPar[1])) -

These come from getFphi / getMaxConsumption:

gadget2/src/stockmemberfunctions.cc

Lines 99 to 100 in 508b993

	grower->calcGrowth(area, Area, TimeInfo, ((StockPredator*)predator)->getFPhi(area),
	((StockPredator*)predator)->getMaxConsumption(area));

...from fphi / maxcons:

gadget2/src/include/stockpredator.h

Lines 64 to 75 in 508b993

	/**
	* \brief This function will return the feeding level of the predator on a given area
	* \param area is the area that the prey consumption is being calculated on
	* \return fphi, a DoubleVector containing the feeding level of the predator
	*/
	const DoubleVector& getFPhi(int area) const { return fphi[this->areaNum(area)]; };
	/**
	* \brief This function will return the maximum consumption by length group of the predator on a given area
	* \param area is the area that the prey consumption is being calculated on
	* \return maxconbylength, a DoubleVector containing the maximum consumption of the predator
	*/
	const DoubleVector& getMaxConsumption(int area) const { return maxcons[this->areaNum(area)]; };

From the calculation of max consumption:

gadget2/src/stockpredator.cc

Lines 158 to 162 in 508b993

	double temperature = Area->getTemperature(area, TimeInfo->getTime());
	tmp = exp(temperature * (consParam[1] - temperature * temperature * consParam[2]))
	* consParam[0] * TimeInfo->getTimeStepLength() / TimeInfo->numSubSteps();
	for (predl = 0; predl < LgrpDiv->numLengthGroups(); predl++)
	maxcons[inarea][predl] = tmp * pow(LgrpDiv->meanLength(predl), consParam[3]);

Hopefully it's true, since it'll be easier to implement in gadget3 :)

[bthe]

Yes, that sort of makes sense to use the feeding level and max consumption, the total consumption is on the stock (at size l) level while the growth should be on the individual level (I guess). But I do have the feeling that the energy content of the prey should be included somewhere, most likely in the feeding level.

On a side note, @vbartolino any idea where the original article is? A quick search on google scholar didn't yield much.

[vbartolino]

On a side note, @vbartolino any idea where the original article is? A quick search on google scholar didn't yield much.

this should be described in Jones_1978_cond_consumption.pdf

[lentinj]

the total consumption is on the stock (at size l) level while the growth should be on the individual level (I guess).

True, although you could work out average consumption of an individual, I was hoping to avoid doing so. And turns out it was worth digging into.

I do have the feeling that the energy content of the prey should be included somewhere, most likely in the feeding level.

The feeding level is in joules, not total biomass as it would be for a (total)fleet. Although I might be misunderstanding the question :)

[bthe]

The feeding level is in joules, not total biomass as it would be for a (total)fleet. Although I might be misunderstanding the question :)

Sorry, yes. Misread the equation ;)