Illegal hunting

In examining the effects of different levels of illegal harvest it is assumed that mortality would affect both sexes and all ages equally. In practice this is not likely to be the case if the hunting is primarily for ivory: it may be true if the hunting is for meat or, for example, if the intent were to eradicate the elephant population. The exercise effectively simulates the impact on the population of a harvest which is spread evenly over the entire population - which could happen in a sustainable cropping programme.24 The 'doubling time' is the number of years it would take for the population to double its numbers and the 'halving time is the number of years it would take for the population to decline to half its original size at the given rate of harvest.

Using a fecundity of 0.25 and a central mortality of 0.5% the population grows at 4.56% with no illegal hunting. The population growth rate decreases with each increment in the illegal hunting offtake and reaches zero as the illegal offtake approaches the intrinsic growth rate of the population. At a 10% offtake the population halves in twelve years.

Illegal hunting has no effect on the setting of sport hunting quotas because the population age structure does not change shape from a stable age distribution. All that alters is the population growth rate. Even when the level of illegal hunting is unsustainable, a quota of 0.5% can be set for sport hunting. Martin (2005) shows that 869 trophy males would be taken over 50 years from a population subject to no management offtakes or illegal hunting: when the illegal harvest is 4% the number of trophies drops to 266.

This is not particularly relevant to the present Namibian situation. Illegal killing of elephants is low - less than 0.1% of the total population (MET 2004). However, should the mood of local communities in the Caprivi change or if people in neighbouring countries decide to obtain benefits from elephants which they are not getting at the moment, it could become highly relevant.

Inexplicably, many CITES Parties seem to think that if elephants are being killed illegally, this is a sufficient reason to ban trade in ivory in the country concerned. The opposite is needed: if illegal hunting is taking place, even greater is the need to trade in ivory to provide the funds to combat the challenge.

Sport Hunting

At the outset, it is assumed that sport hunting will be restricted to male elephants. The implications of hunting female elephants in the safari industry are discussed after the subject of male hunting quotas.

The proportion of an elephant population which can be sustainably hunted to satisfy the safari hunting industry is surprisingly low. If it is assumed that the minimum tusk weight for an elephant trophy is about 15kg (per tusk) and that elephant hunting will not be marketable below this weight, this restricts hunting to males 30 years of age and older. In a population of 10,000 elephants which is not hunted, the number of males of age 30 years and older is slightly over 800 animals or about 8% of the population. This is not the important statistic, however. If one imagines these 800 animals as bulls in a paddock from which it is desired to take an annual offtake, the key factor is the number of 30 year-olds entering the paddock in each year. For hunting to be sustainable, this is the number which cannot be exceeded - and it is about 60 animals per year in a population of 10,000. However, if quotas were set as high as this, after a short while the only animals in the paddock would be the annual influx of 30 year old males and they would all be killed in the year in which they entered the paddock.

The maximum sustainable offtake of male hunting trophies from an elephant population is about one-half a percent of the total population. At this level, there will always be some males in the population surviving to 40 years of age. If it is desired to have a few males in the population reaching 50 years old (at which age it is assumed they will die naturally anyway), quotas have to be less than 0.3% of the total population. To some extent, the hunter is competing with Old Father Time to get a trophy before the animal expires from natural senescence.

Martin (2005) analysed the effects of increasing levels of hunting quotas on the age structure of an elephant population (Figure 21). Martin (2005) built a slight selectivity for animals with larger tusks into the model. The maximum typical trophy tusk weight declines from about 30kg/tusk in the unhunted population to about 21kg/tusk when the quota is set at 0.5%.

The hunting causes the stable age structure of the population to become slightly skewed.in favour of females. For a given size of population (in this case 10,000 animals), the number of males in the 29 year-old age class actually increases from the number in the unhunted population but this is purely an artefact based on the redistribution of the animals in all the age classes to fit the new population profile. The total number of males in a population of 10,000 animals decreases from 4,994 in the no-hunting situation to 4,556 when it is attempted to extract a quota of 0.8% (80 animals) from the population.

Safari operators are able to market the sport hunting of elephant females and will put pressure on the authorities to grant a quota for this purpose. The arguments against hunting females are several:

• The killing of an adult female in a cow herd is socially disruptive.
• As with males, the size of female tusks increases with age (Figure 4) making it likely that the matriarchs of herds will be preferentially selected. The loss of the accumulated knowledge of such older members of the population could affect elephant survival - particularly in arid environments.
• Even where very modest quotas have been set for hunting cow elephant, within a few years of the inception of hunting most of the cows with large tusks will have been eliminated from the population.30 Since the genes for large male trophy tusks are carried by both females and males in a population, it can be expected that this selective practice will eventually lower the quality of male trophy hunting.
• In a long tradition of sport hunting ethics, the killing of females is generally eschewed;
• Elephants, rightly or wrongly, have attained the status of 'totem' animals and any killing of elephants upsets a large public. Sport hunting of male elephants is bad enough: many times more so is the notion of killing females - who will almost certainly be mothering offspring. This becomes a political issue through which entire elephant management programmes may be derailed simply because of the emotions aroused