Aquaculture Research, 2011, 42, 815^822 doi:10.1111/j.1365-2109.2011.02886.x Reproductive success and fry production of the paiche or pirarucu, Arapaima gigas (Schinz), in the region of Iquitos, Peru´ 1,2 3 1 3 3 Jesu¤ sNu¤ nì ez , Fred Chu-Koo , Magali Berland , Lamberto Are¤ valo , Ola¡ Ribeyro , Fabrice Duponchelle1,2 & Jean Franc° ois Renno1,3 1IRD UR 175 CAVIAR, Montpellier, France 2UNFV-FOPCA, Mira£ores, Lima, Peru¤ 3Instituto de Investigaciones de la Amazon|¤a Peruana ^ IIAP,Programa para el Uso y Conservacio¤ n del Agua y sus Recursos (AQUAREC), Iquitos, Peru¤ Correspondence: JNu¤ nì ez, 351RUE J.F. BRETON, BP 5095, Montpellier cedex 05, France. E-mail: [email protected] Abstract Keywords: arapaima, pirarucu, paiche, reproduc- tion, peru, ¢sh culture Arapaima gigas (paiche) is the largest scaled ¢sh species living in the Amazon basin. Its biology is both fascinating and misunderstood. In a context of over¢shing, hence reduced natural populations, Introduction aquaculture of a ¢sh with such interesting charac- teristics (large size, high growth rate, no intramuscu- Arapaima gigas (Schinz) is the largest scaled ¢sh lar spines) is an important issue. The development species living in the Amazon basin (Chu-Koo & of farming production would also reduce the ¢shing AlcaŁ ntara, 2009). It is an emblematic species of the pressure on natural populations and allow re- Amazonian ¢sh fauna, also known as the Paiche in stocking programmes in certain areas. To determine Peru and Pirarucu in Brazil. This species is very at- what factors may in£uence the reproductive success tractive for aquaculture in theAmazon region, owing in captivity, data from breeding reports for 2007^ to its many advantages. Arapaima gigas has the best 2010 were collected among ¢sh farmers in the region growth rate among Amazonian cultivated ¢sh spe- of Iquitos. In parallel, we carried out physico- cies, of 10^15kg per year (Bard & Imbiriba, 1986; chemical measurements in di¡erent ponds where Pereira Filho & Roubach, 2005; Nunì ez, 2009; Rebaza, these paiches breed, and conducted personal inter- Rebaza & Deza 2010), and its ¢let, which is very views about the general ¢sh management condi- popular, does not have intramuscular spines. It also tions. The results show that reproduction occurs accepts low water dissolved oxygen levels, due to its throughout the year but with a higher intensity obligatory aerial breathing. Finally, it has a carnivor- during the rainy season. It also highlights farms ous diet but is still £exible because it can accommo- that have performed much better than others, but date consumption of dead ¢sh or ¢sh feed pellets. no single factor except feeding level has been clearly However, natural populations have been subjected to associated with reproductive success. The environ- excessive ¢shing in the past decades for human con- mental control of reproduction in paiche, therefore, sumption and ornamental ¢sh trading (Chu-Koo & remains partly mysterious. To deepen this study, we Tello, 2010), and already for more than 15 years, recommend the systematic sexing of breeders, ex- A. gigas has become a very uncommon species in the tending reproductive behavioural studies, and exam- Amazon, except in some natural reserves (Pacaya ining the limnological factors involved in fry Samiria in Peru or MamirauaŁ in Brazil). The Paiche mortality. is now in the CITES II list, which means that its trade r 2011 Blackwell Publishing Ltd 815 Reproductive aspects of ARAPAIMA in captivity JNu¤ nì ez et al. Aquaculture Research, 2011, 42, 815^822 and use are strictly controlled. Scarce available infor- inhibit A. gigas reproduction in controlled environ- mation concerns mainly the reproductive biology ments. in the wild (Guerra, 1980; Saavedra Rojas, Quintero Pinto & Landines Parra 2005); however, it is in the interest of ¢sh farmers to develop a controlled pro- Material and methods duction of this species (Pereira Filho & Roubach, Fish origin 2005; Nunì ez, 2009) and one of the collateral ex- pected e¡ects of Paiche domestication is a decreased Between 2000 and 2007, a programme to assist ¢sh ¢shing pressure on wild populations. Nevertheless, farmers in the region of Iquitos enabled the Instituto many attempts have been made in recent decades to de Investigaciones de la Amazon|¤a Peruna (IIAP) to develop its production in captivity (Bard & Imbiriba, provide six paiche breeders to selected local ¢sh 1986; Imbiriba,1991; Alcantara & Guerra,1992; Guer- farmers. Arapaima breeders had been bred previously ra, AlcaŁ ntara, Padilla, Rebaza,Tello, Isminì o, Rebaza, in ponds for 3 years in the IIAP’s facilities of Quisto- Deza, Ascon, Iberico, Montreuil & Limachi 2002; cocha. Pereira Filho & Roubach, 2005; Saavedra Rojas, Quin- Fish reproduction supervising, mandated by law, tero Pinto, Lopez Hernandez & Pezzato 2005), but this started in 2007 and ¢sh farmers had to report to local task is made di⁄cult by the dispersed knowledge on authorities all events (births, fry harvest, etc.)that oc- A. gigas biology in captivity, especially in crucial as- curred in their farms, thus facilitating data collec- pects like reproduction and feeding. tion. Some farms already owned paiches before the Paiche domestication faces the di⁄culty of gender assistance programme; they did not originate from determination, which is virtually impossible from IIAP’s stock but contributed to some reproductive external characteristics except during the reproduc- events. Arapaima breeder weights varied approxi- tive period; otherwise, sex has to be determined in mately from 60 to100kg. blood or plasma samples by biochemical methods using vitellogenin or sex steroid ratios (Chu-koo, Dugue¤ ,AlvaŁ n Aguilar, Casanova Daza, AlcaŁ ntara Fish rearing and feeding Bocanegra, ChaŁ vez Veintemilla, Duponchelle, Renno, The paiches are fed live ¢sh (forage ¢sh), dead ¢sh Tello & Nunì ez 2009). Moreover, the ovary is com- (trash ¢sh from local market) and sometimes down- posed only by a single naked lobe or gymnovarium graded chicken or chicks, ¢sh or chicken viscera, ¢sh (Godinho, Santos, Formagio & Guimaraes-cruz feed pellets and even fruits, although ¢sh-based food 2005; Saavedra Rojas, Quintero Pinto & Landines is predominant in every farm.The amount of food per Parra 2005; Nu¤ nì ez & Duponchelle, 2009) that makes 1 capita (calculated as kg food paiche biomass À )var- the practice of canulation to determine oocyte devel- ied greatly among farms, and most farmers could not opment, induction of oocyte maturation and arti¢cial precisely quantify how much food they had distribu- fertilization almost impossible. As the production of ted to ¢sh daily, monthly or even yearly. For this rea- ¢ngerlings actually relies only on spontaneous re- son, we had to split the farms in three feeding levels:1, productions in ponds, the knowledge of the optimal small quantity (the forage ¢sh are distributed about requirements for reproductive success is a prerequi- once a month); 2, average quantity (the ¢sh are fed site to substantially increase the ¢ngerling o¡er in about once a week) and 3, large quantity (the ¢sh are this region. Nevertheless, a noticeable development fed daily). In the ¢rst level, the food is essentially for- of A. gigas production is expected as most of the age ¢sh consumed progressively by paiches. In the actual ¢ngerling production is destined for aquacul- other two levels, the food is mainlycomposed of trash ture instead of ornamental ¢sh trade as before ¢sh supplemented, or not, with the other cited food- (Chu-Koo & Tello, 2010). This study aims at analysing stu¡s. the reproductive data collected from A. gigas farmers in the region of Iquitos between 2007 and 2010. The results reported here represent the ¢rst attempt Physicochemical parameters to provide answers on the magnitude of a sustained production level of ¢ngerlings with the current The physicochemical characteristics of pond waters knowledge and management conditions. It also were measured within a weekly period for all farms evaluates the variations of some physicochemical during the rainy season (February^March), using and environmental factors that could promote or the Lamotte AQ-2 kit (Drop Count Titration, Chester- 816 r 2011 Blackwell Publishing Ltd, Aquaculture Research, 42,815^822 Aquaculture Research, 2011, 42, 815^822 Reproductive aspects of ARAPAIMA in captivity JNu¤ nì ez et al. town, MD, USA). The following parameters were composed of a few ponds of di¡erent sizes and considered: shapes, including small water bodies created in the carbon dioxide (CO2): absent if values were lower parts of small water streams that drain the 1 o1.25 mg mL À corresponding to the detection abundant rainfall in the area. Most of the farms have 1 limit, present if values were 41.25 mg mL À ; running water almost all year round. A few have lim- 2 nitrites (NO À ): absent if values were ited water £ow or even depend exclusively on rain- 1 o0.05 mg mL À corresponding to the detection falls. The maximum depth is generally comprised 1 limit; present if values were 40.05 mg mL À ; between 1.5 and 4 m (Table 1) with variable £oating ammonia (NH41): absent if values were vegetation cover, and with shorelines generally cov- 1 o0.02 mg mL À corresponding to the detection ered by grass or other small plants, which were ex- limit; present if values were 40.02 mg mL; ceptionally steep. s pH and temperature were measured using a YSI The physicochemical parameters measured varied digital meter (Yellow Springs Instrument Com- within a small range (Table1)and were characteristic pany,Yellow Springs, OH, USA) at 15cm from the of good qualityand soft water. In two cases, pH values surface; attained relatively high levels (6.5 an 8.0), whereas 1 1 hardness (mg L À of CaCO3) levels o60 mg mL À the majority of other farms had pH values around 1 are considered to be low; 5.0 and hardness never exceeded 25 mg L À .